"Not developed to it's potential".
Hmmm, an interesting comment, although somewhat idealistic.
You could equally well say that the 997 C2 is not developed fully, since the GT3, shows that 400 bhp can easily be handled, or if it comes to it, that 500bhp plus is possible with a couple of turbos.
Does this mean that the 997C2 is under specced?
Does it mean that the 996TT was under specced since the GT2, or RUF/Gemballa/9ff, showed you could have more?
Is the Cayenne under developed since the turbo can handle 500bhp?
No car (aside from the McLaren F1 and and the Veyron) are developed without there being some budget or product positioning consideration.
Of course the Cayman could have, and could handle more power. But then so could the 924, 944 have handled more power.
The issue is that if you are going to have a range of vehicles, you need a range of price points and a range of performances.
If you were to argue that the Cayman should cost 70K, have LSD, be stripped out and have 400 bhp, then I would not argue as much (except to say that the GT3 would need to be improved, which leaves little room for the GT2).
But to pitch it at 40K and make it the fastest would be daft.
Lamborghini made sure the Gallardo is slower than the Murcielago (although not by much), AM have made sure the AMV8 is slower than the Vanquish (and I think DB9).
I think the real problem for Porsche is that they have cars in the same niche.
Ferrari have made sure their cars do not compete against each other.
I think the Cayman is an odd car to do from a marketing perspective. The 911 is not enough of a GT car to allow then to do a sports car alongside it.
The real test is whether it is the best car in it's segment. Is the Cayman better than the competition? Although I am not quite sure exactly what it is competing against.
This is the judge of whether it is specced correctly.
However, you also need to consider that the Cayman may not primarily be pitched at the UK market. They are producing global products for a global market. Some products may not be particularly applicable to certain markets.