I was in the exact same spot. I was either gonna go 337 GTI or 20th An, or get an MSP. But after getting on some V-Dub forums and reading up on all the quirky mechanical problems, bad elctronic grmlins, etc, it really scared me. I will have you know that my MSP hasnt exactly been ummm, how should we say *cough cough* "reliable". But i do belive that my case was an isolated incodent, and was the cause of the previous owner, rather than the car.
I would also check on that insurance quote... My MSP is insured as a regular protege and the insurance is lower than it would be on the GTI...
Heres what it came down to... I took a ride in a modded GTi, and it pulled like a mother you-know-what... But rounding a turn we allmost died because the driver wanted to show me how "good" handling of a car it was... yea, not so much.
I then took a ride in another friend 03.5 Blue MSP... It wasnt the fastest car, (he had an injen CAI at the time and was running 9psi on a mbc) and the car still pulled impressivly enough, plus the sound was great. I loved the interior, the wheels, and the shape of the car. The biggest thing that sold me on the car... We came up to the same corner the GTi had allmost spun out at and took it going 20+mph faster without the tires squeeling. I was shaking... but blown away.
Yea, the GTi will walk a stock msp in a straight line... but he will die when he tries to make the corner faster than you!
I got the msp, and even due to my unfortuante luck, have not regretted the decision. We know what a MSP's engines limits are, and you can make sure you dont harm yours while still making it pretty friggin quick... I think you will find it is much easier to build a fast engine, than it is to make a perfectly balanced chassis.
GET THE MSP. PERIOD.