Pasmag did a review of GTA-400m, which seems like a smaller version of GTA-800m. Later this year, the GTA-500m/GTA-1000m replaced the GTA-400m/GTA-800m. The review was very good, so I assume the GTA-1000m is a decent amplifier too.
I am on a fence about buying a Boston GTA mono block vs something else, but $200 would be a sweet price for it. $250 and up is the more usual price for it.
I can get the Boston with wiring kit for $257 and the soundstream by itself for just under $200. I'd prefer used but these seem like pretty good deals.
I ran the the BA GTA 400m and it was a great amp. Sound quality was there regardless of how much I was pushin it. Like others say it seems the SS does rated power as well so really depends if you want the extra 600 watts?