Bryston 7bsst vs 28bsst?

Just wondering if anyone has compared these directly? It seems from what I have read that the 28b's have a significant edge over the 7bsst's more than just more power. I have listened to the 7bsst's but not the 28's. If you do not necessarily need the extra power but have the money, is it still worth going with the 28's?

Thanks