We used to use Roche's TPCK treated Trpsin ourselves. When we developed our Trypsin (~2001) and before release we did compare ours to both Roche and Promega Trypsin. Our results suggested that when doing routine digests of less than 24 hours at 1:20 enzyme to substrate ratios, all three were relatively equal. However, on extended digestion (up to 7 days) at 25°C or 37°C, which simulates long term storage of digests both Roche and Promega had an undesirable protease activity (not Trypsin) that was observed to degrade some of the peptides. As for Invitrogen’s Trypsin, it is intended for trypsinolysis of cells, while ours is for proteomic applications. You could use ours but it would be 100's of times more expensive because of its level of purity. At present we offer no substitution.