Everybody here got good points. The other things to consider is that even with a car in prestine condition, it will cost $$$$$ more to maintain and set up. Even if you only use it in good weather, the GT3 is more sensitive to alignment than the Caymen so an immediate check is required. In addition, the coolant fittings are a known potential failure and if car was tracked new LSD may be required, and a few other maintenance items that will be required on a 5yr old car.
I think everybody can agree, if you dont have a healthy budget for maintenance, stay with what you have or look at the new Cayman.
Good luck and let us know the outcome!

I would say do it. I did much the same thing but I had a 96 993 and a 2008 911S. I don't regret it and while I wish I could have kept the 993 I own my dream car now. It really is better than both of them put together IMO. It's also less insurance, less maintenance and less to worry about.

Don't give up both cars for a GT3.

Maybe it would be more affordable to keep the M3 and trade in the Cayman for a 997S...

I guarantee you will miss that high-revving V8 quite a bit.

Decided to keep my M3.

The fate of my Cayman is unknown. How much more driving enjoyment and involvement does the 997.1 GT3 offer compared to my Cayman S excluding the obvious power difference? Considering my limited budget, would a 997S be closer to the GT3 or Cayman from a driver's car perspective?

No comparison. Owned a CS for 2 years and traded up to the .2 GT3. NIGHT and DAY. On my favorite high speed track (AAA Roval) it was worth 7 seconds between the increased power, aero and confidence. Cayman was on R compounds as well with light mods.

If you can find a GT3 to drive that will be the best way for you to answer your question. good luck

Coming from a somewhat modified E92 M3 to a 997.2 GT3, there is no comparison on the track. It is simply a whole magnitude of difference. There is no way I could daily drive the GT3 though. I think it would rattle my teeth loose.

I had an 08 Cayman S for three years and an 11 E92 M3 for about 9 months. M3 had an amazing engine and makes a great DD but not a lot of fun on the track though it held up much better than my E46 M3. I was starting to get worried about the CS motor as it saw a lot of track time and the pre09 cars are prone to oil starvation. I considered buying a 997 GT3 but ultimately went with a 991S 7MT. Very happy with my decision so far and am looking forward to getting in on track soon.

Good decision to keep the M3 you need a good DD with some spirit...

Consider going to a 996 GT3 from the Cayman. Cheaper buy in and one of the most exciting raw drivers cars out there. I don't think the 7C2S would be enough of a difference from your M3 to give you the same thrill the 6GT3 will. When budget allows jump to a 3.8 7.2 GT3

I would go the 7.1 Gt3 and sell both m3 and cayman S.

The DD would be a decent hatchback (not camry).

In fact, I keep thinking about selling my boxster spyder for a 996 Gt3 or 7.1 Gt3. My 7.2 RS is getting too precious to track and I know how awesome a GT3 is.