My sales rep gave me the unbiased truth about the differences between the gem labs' certifications, and how they're not all the same. I also received unbeatable pricing that no other store could match, given their low overhead. She even called me up literally within minutes of a stone listed on the dealer network that was close to what I was looking for - she didn't merely take her time or just push a stone they had in inventory. And while most bricks and mortar stores might have a few wholesalers/cutters they work with (limiting the variety they can offer you), Whiteflash has a much more significant inventory they can offer you, so you can get the exact stone you're looking for.
I ended up buying a superb stone for my fiance (3.17ct, G SI1, AGS-certified 000) at an even better price.