I too would be VERY interested in the real-world skinny on these, both the kind you can tile-on-directly, and the kind that are finished, ready to go. Either way, the PRE-SLOPE and CURB are built-in! And no "membrane" required. BRAVO! I've "heard" good things about the Swanstone bases (~$300), and for ~$600, the nicer Corian bases, both ready to go, in MANY color choices. You bring your cement-board + tile right down over their side-flanges, caulk the seam, fit the drain spud--DONE. NEXT. (I've heard there are also Corian wall panels, which obviate tile altogether.) Basically they are bathtubs, with very low sides. You never have leaks from bathtubs, sign me UP!... lol. I am totally turned off by the time and labor involved in "mudding in" a custom shower base, Kerdi or "traditional"... friggin' membranes, weep holes, which "religion" to follow on curb construction, what kind of whiz-bang grout to use... on and on... I RESPECT the skill involved, but who needs it?

You might want to repost your question to the GardenWeb Bathrooms forum: http://ths.gardenweb.com/forums/bath/ I posted there when I was looking at different composite base manufacturers. Not only did people respond who had chosen and lived with different models there are also lots of past postings on the subject of different types of showers. Based on what I've read, I have to agree with macv about the higher quality of a composite base over an acrylic. We're going to go with a composite for our upcoming remodel.

Kohler calls its ready-to-install, complete, shower-ready pans that need no tile - acrylic, acrylic over concrete, and cast iron enameled - BASES. Here OP, I am going to guess that if the description discusses the finish or color, they are not to be tiled. Could it be that the people you were seeing discuss putting tile over their bases were talking about tiling the walls above their Kohler bases? That is a common practice. All the bases on the page that you linked to are complete bottom-of-shower pieces. I have a solid surface base from Transolid that does not have strips on it. It was cut to resemble 2" tiles, so that there is not a solid sheet of plastic, that can get slippery, underfoot. Solid Surface is a term that indicates that there is a plastic composite material that is the same through-and-through, so if it should ever get chipped or scratched, there is no different colored substrate. The surface can be repaired or sanded if needed. They are more heavy, reliable and expensive than the acrylic bases and last pretty much as long as the cast iron bases. Look for Swanstone, Corian, Transolid and other manufacturers. If there is a surface treatment like a gel to make it shine, it is not solid surface. Here is mine:

@Liz Court, we ordered our custom shower pan from Grifform. They are very helpful/responsive if you have questions. If you decide to move forward with a Corian shower, please create a new post and I'll share my tips/learnings. Meanwhile, do a search for Corian shower on this board and you'll find my previous posts with pics about some of the issues/hiccups/drama I encountered during our Corian project. For our walls, I reached out to the regional Corian distributor and asked who in my area fabricated Corian showers (there weren't many). I got three quotes which varied widely and I went with the middle quote who happened to be the closest to our home. Hope that helps!