Today you can buy "mass spectrometry grade" trypsins from a bunch of vendors. Are they all the same? How do they perform on easy stuff (HeLa cell line digest) or super hard stuff (single cells and plasma)?
On the list of - thank you for doing this because it sounds like zero fun whatsoever - check this out.
I won't ruin it for you, it is a fun read, but on the easy stuff, maybe it isn't a problem. On the hard stuff, there do appear to be some differences - and there is some evidence that you should really keep it consistent (don't swap trypsins in experiments). The thing I found the most alarming was the decrease in trypsin performance at recommended storage conditions. While the authors indicate that this decrease is within their error bar, it is still a drop. We'd do this thing in the government of buying lots of trypsin right at the end of our fiscal year -- and sometimes it was a LOT. Like -- years worth. If you don't spend that money it goes back! With detection of a decrease in performance over a period of months it may make you very concerned when you are keeping some surplus trypsin over a course of years.
Solid, well executed work that answers questions I think just about everyone has wondered about and I sure wasn't going to ever do it!