I used to own an MP, sold it, don't miss it.
I agree with Frank Petronio really, 35mm is great for tiny, convenient cameras, but for medium size cameras such as Leica, you may as well go medium format, the cameras are not any bigger, sometimes smaller.
A Zeiss Super Ikonta III will give 6x6 negatives and is cheaper, smaller, and lighter than a Leica M. A GF670 is only a bit bigger than a Leica, folds up small, has AE, and a fraction of the price of an MP.
Mamiya 7, Rolleiflex, Plaubel etc. are all great options too. If you're happy with the T3 (I would be), then the Leica MP is a way of hoarding money for no reason.
On totally the opposite side, the heart will always want what it wants, and you may feel that a Leica is the only camera which will satisfy you. I don't feel that way, but totally get that for some people only a Leica will do. I get it, I understand it, and you don't have to fight it.