2 years off and on is somewhat hard to gauge. does that mean 2k, 5k, 10k+ miles? the less miles you have under your belt the more i'll lean towards sticking to the bike you know. small cheap and used for the 1st bike is my mantra. altho the maxim is a 4cylinder which i dont recommend for learning. but since you've already got some miles on it without killing yourself...
and since noone has mentioned it. if you havent taken the msf course i'd highly recommend it. i know some states dont require it. but there are some good skills to be picked up in that
which of the triples are you looking at, the 800 or 1200? have you ridden one at speed for any length of time? have you looked at the ducati monster (both the 800 and 1200) or yamaha fz-09 or suzuki sfv650, kawasaki z1000, harley vrod if your going to spend 10+k on a new bike you should look and ride everything you can.
personally while i dig the looks of the streetfighters, a fairing and windscreen are much more comfortable at interstate speeds. maybe the cbr650? fz6r, fz8 or fz1, ninja 650/1000 (ex models),
as for the price of the maxim. well finding bike that runs well, doesnt need work and you dont need to mod for under 2grand isnt the easiest task. how many miles are on it. does your dad still ride it, does he have other bikes he rides. is that figure the down payment on something to replace the maxim.
and dont forget to figure in the insurance costs of a new 10k sport bike. depending on age and the bike that you choose that may be a deal breaker.