RE: which bow to buy??
Can't comment on the Diamond, but I have a TomKat myself. Great bow, period. Nice brace height so its very forgiving. Would be great for a "beginner" as well as a seasoned shooter. Its fast and quite.
The only "bad" thing I've seen anyone say about the TomKat is the grip. I also agree that you would probably want to put a custom grip on it.
If this is the bow you decide to buy, buy the bare bow. Not the package b/c you will end up replaceing everything on it with "better" stuff anyways.