Scott,
Okay, strictly between those two choices, I would go with the Anthem given the prices. You know, the primary purpose of the monoblock design is to have a better regulated, current-tolerant power supply. So, the Sherbourn's design doesn't make lots of sense to me if it has the rated power of "only" 200W/300W to start with (as compared to 200W/350W of the Anthem) -- now, I do note that Sherbourn specifically stated that these numbers are with all channels driven. However, the very advantage of the monoblock design dictates that it will NOT perform much better than that with only 1 or 2 channels driven -- i.e., the Anthem will beat it at least when compared 2-channels-driven. Incidentally, even my lowly Adcom GFA-565II delivers 200W/325W, conservatively spec'ed.
With regard to the intentional fudging and "under-spec'ing" of 8-ohm ratings, I don't think the manufactures would ever do that -- after all, the 8ohm power rating is still the primary number with witch an amp is "labeled" and marketed. I don't think that, at this price range, the manufactures cannot afford to overtly over-spec the power output, either (unlike in the market of much lower priced AV receivers) -- their brand image is at stake here.
Both amps seem to be solidly and beautifully designed; both brands are well established and highly respected -- I don't think Sherbourn has a good justification of the additional US$600-700 here, IMHO.
Now, I don't have any experience or information regarding their reliabilities.
