I drove a 2.5, then a 2.7, then the 3.2 S that I bought. Pricing for S vs non-S isn't much different in my area that I've seen...so bang for my buck, I got an S.
There is a difference with 50 more hp.
To add 50 ponies to a 2.5 or 2.7 would cost you more than what you paid for your car originally. Just price it out...you'll see.
If you want to go blazing fast in a straight, boring way then I suggest buying an old Nova and add a giant V8 and a set of slicks.
Oh, and +1,000,000...go learn how to drive these cars. You won't regret that.