I've used a number of Michelangelo mouldings here. On the whole, I haven't had too many problems with their product; at least no more than other framing companies. Sometimes there will be twisted/warped moulding, sometimes the finish is not quite perfect. I've never purchased a box of moulding - I just buy length from my local framing distributor as I need, so I can't comment on the quality of the moulding for a whole box. The price point is quite good.
It can be hard to use up left-over 'black' finished moulding with a new length because the 'black' colour can differ - more or less gloss/darker or lighter black. I haven't really noticed this inconsistency too much with other profiles.
Another thing to be aware of is back-order issues. Although, this has only happened to me once in the 5 years that I've been buying Michelangelo moulding, it was bad timing. There are a few black profiles that I use fairly often and they became back-ordered just prior to Christmas one year and took a long time to come in (3 months if I remember correctly). Yes, I know I should have planned ahead and had some in stock, but up until that point I never had a back-order issue with their product. I know better now.