this one's interesting.
I sold my MSP (with roughly the same mileage) for about $6k a couple years ago and got an MS3. While I wouldn't go as far as saying I regret it, part of me definitely feels I would have been better sticking with the MSP. Here's why.
Cost: Aside from the LSD, I had all of the usual suspects replaced (timing belt, clutch, etc) so, even though it was up there in mileage, I wasn't overly concerned about high repair bills suddenly showing up. Looking back, if I had kept it, I would have been proactive and had the LSD replaced. In the end, I would have been out about a grand but, since I didn't owe any money on it (I'm presuming you don't owe any on yours either) the true cost of ownership would have been nothing compared to buying a new car. Fast forward a couple years and, while I love the MS3, I'm knee deep in payments while the mileage is racking up even faster than with my MSP. At the rate I'm going, I doubt I'll get to the 80k mileage range totally paid off like I had with my MSP. That sort of tells me it wasn't the best financial move.
Handling: It's been mentioned before but needs to be mentioned again. Some may assume the MS3 handles better than the MSP but it's just not the case. Obviously they're 2 completely different cars. The fact that the MSP weighs less and (in stock form) is lower may actually lend to the perception that it handles better. I don't know... and I don't care. Perception's everything and, even with the swawbars and everything else I've done to my MS3, the MSP definitely still felt more like a go kart while the MS3 feels more like a... big car with a big engine.
Interior: This may actually surprise some but I actually think the MSPs interior is slightly better in the quality dept. I know I know... call me crazy. It's not that the MS3s is bad. Looks and layout wise it's great... though that sort of thing is subjective. I just feel the quality of materials is slightly down. Like the plastic is half as thick or something. Hard to describe... let's just say I didn't hear nearly as many rattles with my MSP. Everything just seemed to be tighter.
Hatch practicality? For me, this is over-rated. I'm the kind of guy that practically details his car every week. I want my car to be in like-new condition as much as possible so I go out of my way to keep it clean inside and out. that means, if I have to haul something, I'm probably not going to throw the seats down and load up my ride... instead, I'll just use my wife's element. So for me, the whole hatch thing really isn't much of a benefit. You may be different but, if you don't think you'll be hauling anything more than ass, you might want to factor this in as well. All things being equal, I'm more of a sedan guy. I purposely don't keep much back there since it's sort of a PITA (compared to simply opening a trunk) to raise the entire hatch up... especially if all you're looking to do is grab something quick. idk It's like the different between opening a screen door and opening a fireproof, steel 'you're not breaking into my house mofo' door.
So there's my take on it. If the MSP fits you (meaning you're on the young side and the whole fast & furious look doesn't affect your job/lifestyle) I'd definitely urge you to consider sticking with it. The performance difference, despite what you read in reviews and see on spec sheets, isn't really THAT big a difference. Sure, the MS3 is fast but it's not Lamborgini fast. When I bought my MSP, one of the reviews that helped push me over the edge stated that it FELT faster than a WRX... even though on paper it wasn't. So true. Maybe it's for this reason I don't notice as big of a difference as there really is. Of course, I'm not racing punks (which, in turn would make me a punk as well) so I don't have that as a reference point.
Anyway... good luck. Even though there's no looking back... in the end, it's just a car so... yeah, not the end of the world if you end up with a slight case of buyer's remorse like me. Definitely can't go wrong either way.
