Most sold now will deinterlace (though some earlier models like Samsung 170/171MP did not), anything sold as EDTV, HDTV, "upconverts", etc. Amiga laced screens may or may not be correctly displayed, though. I've also found a few region free LCD TVs that couldn't handle Amiga PAL output for some reason. There's also the issue of most smaller LCD panels being 16-bit, not correctly displaying the AGA palette.
Best option would be to try before you buy, as it is a complete crapshot. IMHO I'd hold out for an Indivision if at all possible, it could save a ton of headache. (I spent a small fortune on TVs, signal converters, etc the last few years before the Indivision was released.)
*edit*
Problem with the scaler you linked to is the 50 -> 60Hz framerate conversion, which will bork the scrolling in all your games. Might not be much of an issue for "serious" apps, aside from the possible screen glitch in 50Hz modes. (Framerate conversion might still affect static screens with annoying artifacts.)