If I was in your position I'd get a T3. For Jewish/Chassidic music there isn't much of a difference. Most of the Jewish performers I know do not think it is necessary to upgrade.

That said, I do plan to upgrade since firstly I get lots of use out of it, so its worth it for me; and secondly because there's one new drum kit I think is a step higher than the T3. Other than that, the T4, really is a T3.1

Chony