The decision should be based on the reasonably expected work load. I do not see the T4 as having lower quality. It is just designed for a lighter work load.
RE: “I know I have seen some video where they explained that if the knife blade is very thin, you could measure the angel to the knife jig. But i cant find it, was it -10° on the angel or something like that?”
Lack of coffee I suspect, but I’m not sure what you are asking. Could you please clarify what the problem is?
RE: “Also, is it the same for both knife jigs?”
Do you mean the standard knife jig vs the long knife jig? If so, yes. It’s the same.
Jeff55, what do you mean by “thick blade knives”?