I replaced mine recently, definitely worth it in my opinion. Really cleans up the appearance and no foam "dust" falling down all the time.
I bought an aftermarket from this web site, and used 3M Super Trim Adhesive. An 18 oz can was just the right amount.
Drape some old sheets over the engine compartment and windshield before you scrape off the old pad, it gets messy.
And put the sheets back before you spray the new adhesive. I got some dripping but no problems with overspray, it's more like "silly string" than spray paint.
By the way -- I didn't try to get all the old adhesive off... I figured I'd end up ruining my paint job with stray solvent or something. So I just used a dull putty knife to scrape away all the old foam. So far (several months and quite a few miles) I've had absolutely no problem with it sagging or pulling away.
I would definitely recommend a helper... I don't think I could have attached it as neatly without one. It was particularly tricky sliding it under the sheet metal along the bottom of the hood.
And oh yeah, I did make one gratuitous addition to the hood pad before assembly...