Honestly. The only way to match the sound quality of floor-standing speakers requires an investment in a box that goes into the wall that the speaker can be mounted to. Shock absorbing ability and throw distance for the drivers demands a hefty influx of technology that cost money. Without this sort of attention to detail, all in-wall speakers probably sound the same. I'm not a big fan of permanent home theater structures, but the Paradigm Signatures sound pretty good for in-walls. The problem is; They cost as much as the floorstanders. Also, with in-walls you run into the same problem as placing a good floorstander too close to a wall....muddy sound. I'd rather use the speakers from the TV than waste my money on in-walls and in-ceiling speakers.
"The challenge is to get people into situations where they can hear
good demonstrations of multichannel entertainment, using good
equipment. The entry-level in-wall/in-ceiling systems, and systems
with inadequate tiny surround speakers can be impressive if one is
easily impressed. However, those of us in the business need to show
customers that much better sound is possible, and sometimes for only
modest cost increases. Good in-wall speakers exist, but they are not
inexpensive. Ceiling speakers are for background music systems in
stores (I exaggerate, but only slightly). Ceiling speakers should never
be used for the front channels, and used for surround channels only in
homes that I am never invited to." - Dr. Floyd Toole
So wouldn't you argue that if the Paradigm inwalls sound as good as the floorstanding and are priced the same that inwalls make sense, in the very least saving space? I agree that inwalls in general are a compromise, however there is some pretty good stuff out there.
In-wall speakers are designed specifically for that purpose, including the fact that you will have loading from the wall itself. So, basically, it is a matter of how much money you want to spend, just as you would with regular speakers. I would suggest getting in-walls that have their own enclosure (it fits between the studs). That way, the sound won't be affected by how far above and below the speakers the cross stud braces are located, and there won't be as much noise from the studs making noise where they are nailed to each other.