This is pretty much a rhetorical question. I agree that if money is an issue (and it usually is) there's absolutely no need to worry about buying or upgrading to the T5. But in the same time, if the money isn't an issue (congrats on that, BTW), I see no point of not getting the T5.

The fact is that the progress is still going on. Let's say, there was the time when all the arranger keyboards sounded like toys, and now they sound like real bands. Did it happen in one moment? No. It was one step after another. And now T5 is one more step after T4 towards the future.