Theres no way you can predict what insurance quotes will be like a year down the line. Yes, they should go down with more experiance and NCB but this isn't always the case.
Like you, I went for the 2.0 Gti as I refuse to pay big bucks for insurance (anything over £500 is a nono). I seem to remember you paid £5500 for it?? If so, that is top book and changing so soon will mean you taking a big hit in the pocket. I got mine around the same time as you and paid similar money (tho mine has anni kit, santas and 36k), I intend keeping this for at least 3 years. Maybe I'll go the turbo route then but I'll probably be looking at property then so an old banger will be my wheels.
Just out of interest, would I notice I big difference if I drove a 1.8T when compared to to the 2.0Gti? If so where would I notice this? (ie topend, midrange etc) I find mine fast enough for what I use it for, and it does look the business (pics elsewhere on here)
Matt