Welcome to the Brotherhood, Mark! You may find the non-TTL finder just fine, since the TTL meter is full-area averaging, and not as accurate as a hand-held meter, in my experience, at least.
As for image quality, it's all there, but you may find all your errors are more obvious as well. The shallower depth of field of the longer lenses makes focusing more critical, for example. Well, if it was easy, everybody would be doing it, right? Pat White