I would buy based on which bike you want. The 1100 and 950 are in the same price range. Horse power and torque are not much different. While the oil filter thing is a problem it is one of the few flaws of an 1100. The bike is a proven bike, looks good with that traditional look, and is very reliable. Been out longer and so lots of accessories are out there for it. 950 is smoother, better balance and injected. Still looks good. 950 is taking the place of the 1100 which is being phased out.
The two into one is not as cool looking as duel exhaust but two into on actually gives a little power boost. The stock pipes sound good but if you want louder then there are aftermarket.
1300, a little more bike, and is water cooled, injected, good balance, More money. Has been out for a wile, you might find a used one.