Anyone have any experience with them?

How light are they?  Do they stay put? Are the rails durable?

I like the concept for mounting lights, VFG's and other non-optic accessories, but am curious if they hold up well to regular use.

I have the Tapco Intrafuze front handguard for an AK. Fits fine, and locks up tight, BUT... that rail cover for the bottom is a POS. Utter junk. The retaining tab does not hold tension at all, and will slip right off when just holding the weapon. I had to add a pop rivet. It is also kind of skinny, but thats normal on the AK. The rail is just polycarbonate plastic, and would hold minor accessories if you don't plan to take it off much.

I like the heat shield, and to have an option for a rail, but that intergrated cover is junk.

the ar ones, at least my set don't have heat shields.  they seem to work and look kind of cool.  i have the set on my girlfriends rifle which doesn't get shot much so it's perfect for her

for looks they are ok i guess  but i would not mount any thing on them like a laser and your fpg might wiggle some or a lot

My experience with Tapco (I have a bunch of it on my Saiga) is that their stuff is fine, but feels pretty cheap.

If you're wanting an inexpensive forearm that doesn't require removal of the barrel nut, many people are quite pleased with the MagPul MOE handguard, and my experience with MagPul is that their stuff is a little higher quality than Tapco, though I have no personal experience with the MOE itself.