I have Polk RC inwalls in my bedroom system, and like garcianc says, the bang for the buck is nice, considering decent inwalls have gotten very pricey of late. However, I wouldn't put them in my main system. Basic Polks will get you there, but if you're thinking in audiophile terms, you might want to consider Triads, psb's, or even Polk LCi's.
Other than brand, here are some considerations I learnt about inwalls:
- Determine the placement and location on the wall before choosing a speaker, and be sure to avoid sharing wall cavities with existing wiring if possible. Also, check the depth of the wall cavities in all locations to ensure proper fit (I used a long BBQ skewer - clean, of course).
- More expensive speakers have enclosures (like nicer polks and triad InWalls). Build an inwall enclosure for basic inwalls to get the best sound. Dense wood bracing and insulation can help eliminate typical sonic issues for inwalls.
- There are a wide range of speaker sizes and performance, so choose a good brand with the best performance you can afford - it won't be so easy to upgrade these things.
- If you think you might ever sell the house, you're (most likely) selling the speakers with it. Inwalls are a nice selling point, but you won't get anywhere near your money back on pricier models.