I had the same problem. I hated the new Rubicon I bought so I traded it on a King Quad 700. Lost my butt, but the 700 has alot of power for only about $700 more than the 450. I'm not sure about long term yet though. I hope it stands up.
Buck

 

I've got the Kodiak 450 and I did have to lift and widen the bike to get it up to the standard of ridin' I like. But I also got this one because I was upgradin' my 400 Kodiak with the straight axle to the 450 IRS. Yes... I also got the infamous Brake Squeel" that I got on my previous 400 (fixed with a $30 aftermarket set of brake pads) but, my brother bought a 2 up Sportsman 500 and has had nuthin' but "Pull startin', Axle snappin' FUN!!!"

 

i have some seat time on the 660 griz, 700 KQ, 450 KQ, and big bear (mainly from friends we ride with). i persanaly own 2 suzuki vinson's............the 500 suzuki is a hard engine to top! i would strongly concider the AC 500m!! same engine as the vinson! here's a good 500cc review ( http://www.powersportsnetwork....rof_review.asp?code=85 )! with quads getting larger and larger (why i don't know), a 500 is about the minimum i would go. it's not to small for a work hourse, but it's not a high dolor big bore. of the ones i rode (other than my vinny) i favored the 660 griz........the KQ lack in the low end grunt (as i'm not the only one to notice this). you can put modules and clutch kits in them to make up for it, but my friends 660 has a good amount of low end grunt even pulling 27's!

the EFI has a snappier responce, and will not be as much of a hassle when it comes to changing elivations! BUT with a carb, you can always upgrade with a dial-a-jet (soon to be added to my vinny) so jetting isn't as much of an issue as you think. for $60-70 it's not a bad upgrade, even for a stock bike.

and if you look into them you can probably find a great deal on the vinny or the AC since this is the last year for the 500 engine........i had to wheel and deal to get dealers down to a "rock bottom" price. i know a couple guys that went in with 90% cash and bought a vinny for 300 less than what i got mine for (purchased mine for $5100 sticker price).

 

A friend of mine has a 500 vinson. Man, what a good lookin' bike!!! The headlights and speedo pod are sharp!!! If I wasn't so brand loyal the Vinson or the King Quad would definately be my bike of choice!!! Black is pretty stealth lookin' too. the Kodiak SE I had before this one was black and silver. But still not as easy on the eyes as your Vin with the C-Series ITP wheels. Good for you!!!

 

I will never own anything else besides Arctic Cat since i bought my first one. Get the AC, you will love it

 

Consider:
You can get a leftover '07 KQ700 for the same price as a '08 KQ450... same chassis/size, bigger motor.
Grizz 450 is physically smaller, but a proven reliable machine (and a bit of a dog).
AC 366 will out-perform an AC 400, and is the ONLY AC that isn't overweight.

 

It all depends on priorities.
450 Griz: Best auto tranny in industry, most manuverable due to smaller size, excellent brakes, totally proven with zero surprises.
450 KQ: EFI nice if you regularly ride in radically different elevations, no bargin.
500 AC: I personally do not like linked brakes, If you can live with the 500 5 speed then you will have one of best performing and most reliable machines on market, wider and heavier so more hassle in tight situations, most wheel travel and ground clearance so the best in big rocks and logs and mud.