I have owned cars with 0-60 times in the low 4 secs (Mercedes E55 AMG Kompressor and Chevrolet Corvette C6 X51). The thrust on full throttle is very addictive but the reality is that road cars does not need this level of performance to be fun. I now have owned my 987.2 Cayman S for 9 years, and it can deliver addictive thrust when needed, not quite in the same league as my former drives, but still great fun. A sub 5 second scream to 60 is not important on the road, what you need is a good wide torque band giving a strong pull from moderate revs. The Cayman's 3.4S lump does just this and, yes, I have been tempted to upgrade over the years, but the reality is that I would be unlikely to enjoy a GTS any more than my 987S, and probably would not achieve any better A to B times on a good clear driving road (certainly not any better on typically congested roads). This really is a case where I believe that less is more.
Mark, save some money and broaden your choice by looking at a 991.1 S or even a 981 Cayman S for even more fun.