Bying 2nd hand - 2T or 4T



I am looking to get an mx bike for weekend track riding with friends. I cant afford to get a new bike but will have to go for 2004 250 2t or 2003 250 or 450 4T (or older). Ideally I would like to get a 4T because i find them much easier to ride and imagine i will learn faster on one but i am concerned that (as i will have to get a secondhand bike 2004 or older) these will be expensive and a lot of work to maintain. Although i havent worked on mx 4t engines yet, i am fairly confident that with a little time i´ll be able to do most work on the bike myself.

My question is essentially this : given that i have to get an older bike, what sort of troubles should i expect with a 4t? Would i be better off with a 2t?

1) your physical size : 72kg, 175cm
2) How physical / aggressive are you ? pretty aggressive
3) what do you plan to ride : mostly track, possibly a little enduro
4) Do you have any riding experience? lots of offroad adventure travel and have messed around on a cr250r on and off track for about 1/2 a year.
5) Do you think you will race ? Maybe
6) Are you mechanically inclined and will you be doing your own bike work? Yes - i´ll be doing my own bike work
7) Do YOU have a preferance to a brand/ motor choice (2 or 4 stroke)? Not really - I like both, but find 4t much easier to ride.
8) Do you have a dealer close by your home that you might use and what brand(s) does he carry? yes - all bigger brands
9) How much do you plan to spend on a bike? enough to get me a 2004 250 2t or 2003 250 or 250 4T here in Norway.
10) Do you live in California? no
11) anything else that you think would help form an opinion