You want some specifics on how 646 PLUS out-performs:

note: 646 Plus and 686 Plus performance AND test data is the same except for #5. The only main differances are the level of shine.

(1) We did a side by side early water-resistance test with a name brand sealer marketer that rushed their new low v.o.c. sealer to market, kicking and screaming all the way. These marketers wanted to continue selling high v.o.c. products, but they were required to sell only low v.o.c. products.

We did a test to show what would happen if it rained shortly after applying the sealer. We applied 3 coats of the marketerís sealer on one side of a slate, and 646 PLUS on the other. We let them dry for one hour. Then we submersed the slate in water. The marketerís side totally failed within minutes with water resistancy. 646 PLUS totally rejected the water. Then we let the slate sit for 2 hours. We then removed the slate, and let it dry. The marketerís side was soft, opaque, and damaged. It would have to be stripped. The 646 PLUS side was undamaged. We do not suggest you seal knowing 
rain is on the way, but you can do this test, and see the superior performance.

(2) The hot tire tests performed with these resins show superior tire mark rejection than two part epoxies used to coat auto service station work areas. No low v.o.c. acrylic sealer comes anywhere close to this performance. Bear in mind that sealers can resist tire marks, but no finish will totally reject tire marks.

(3) There is another fancy marketing company with beautiful packaging. They have some company produce their low v.o.c. products for them. We tested side by side with this product in the area of re-coat. We applied a coat of the marketing company's sealer to one side, and 646 PLUS to the other side.
When visibly dry; we applied a second coat. The marketing company's sealer streaked, and formed ugly white crystals. If you applied the marketing company's sealer carefully, and just right; you would get a passable shine.
646 PLUS went on smooth, and looked beautiful. The look was that of a wet glass-like ceramic tile.

(4) We also looked at the human exposure factor with the company mentioned in (3) versus 646 PLUS. The marketing company sealer has a strong benzyl alcohol smell. 646 PLUS has a relatively low odor. With 646 PLUS we formulated with the newest, safest chemicals available.

Why the concern of the candy-like odor of benzyl alcohol? Let me take quote from a benzyl alcohol material safety data sheet. "...WARNING! HARMFUL IF SWALLOWED, INHALED OR ABSORBED THROUGH SKIN. CAUSES IRRITATION TO SKIN, EYES AND RESPIRATORY TRACT. AFFECTS CENTRAL 
NERVOUS SYSTEM...." "...Potential Health Effects: Inhalation: Causes irritation to the respiratory tract. Symptoms may include coughing, shortness of breath. May be absorbed into the bloodstream with symptoms similar to ingestion. Ingestion: Large doses may cause sore throat, coughing, labored respiration, dizziness, dullness, abdominal pain, vomiting, central nervous system depression, convulsions, and death due to respiratory failure. Skin Contact: May cause irritation, redness, pain, and tissue injury. May be absorbed through the skin with symptoms paralleling ingestion. Eye Contact: Causes irritation, redness, and pain. Can cause eye damage. Chronic Exposure: Chronic exposure may cause skin effects. ..."
***(quote from - )

Bearing in mind that we at Duro Shine Sealers LLC are formulating with the safest chemical solutions available; sealers are all products that have some level of toxicity, and should be handled, and used carefully according with the protective measures printed on the bottle, and at the web sites. For any further concerns; contact the manufacturer of the sealer you are using.

(5) For clarity, depth of color, and the enhancement of colors. We have tested several name brand semi-gloss low v.o.c. sealers, and find none that match our look. We were the first company to come out with a semi-gloss sealer, and we do not use wax coated flatening agents. They give a lifeless look to the finish. We use a proprietry blend of chemicals which we make to lower the shine. We took into consideration level of gloss, and depth, and clarity of the finish. The end result is a very beautiful  finish.

(6) Most of the name brand low v.o.c. products we tested were less hard than the higher v.o.c. products. Regular acrylic products need alot of co-solvent component to form a hard film. You need to lower the co-solvent to make the product low v.o.c., consequently you end up with a softer, less durable plastic. 646 PLUS uses a self-crosslinking acrylic/ Poly that requires very little co-solvent to form a very hard surface. We observe a superior hardness in 646 PLUS. Bear in mind that these are all plastic coatings, and subject to scratching.

(7) 646 PLUS is a breathable coating. That means that vapor pressure below the stone can force it's way to the surface, between the molecules of plastic. Oil based lacquer is not breathable, and should not be used on exterior walkways, or floors where vapor may travel up from the earth through a slabe. 646 PLUS is non-yellowing, where oil based lacquer darkens, and yellows. 646 PLUS makes oil based lacquer obsolete. Shouldn't be a surprise. Lacquers have been around since the 60's. How many eight track tapes do you have still around. Technology marches on, and innovators bring you the latest, greatest solutions for today's needs.

(8) If you currently use an oil based lacquer; check the packaging. If it says " not use where hydrostatic pressure exists..."; do not attempt to use on a floor, unless you are sure no vapor pressure exists. Most floors, and exterior surfaces need to release vapor (hydrostatic) pressure, and require a breathable sealer. 646 PLUS is a breathable sealer.

(9) Marketers have someone else manufacture a product they consider sellable, and dazzle you with great marketing. It's all about hype, and market share, and no attention to quality. We at Duro Shine Sealers LLC spend a great deal on research, and development. We manufacture our own superior products, and now bring you a new generation of sealers