It's funny, my brother has a 55 plate S2k, what's deemed as the sweet spot with the chassis tweaks to dial out the snappiness but the lower tax cost and I have the Chimaera, my 400 is similar in power to the factory figures quoted for the pre-cat 4.3 Griff (but in all likelyhood about 20bhp up as mine is dyno tested and not TVR quoted and they liked to exagerate). The 4.3 will sound better though as mine still has it's main cat although the pre-cats are gone. I like both for what they are but chose V8 power, because I'd had so many 4 pot Honda screamers I wanted the TVR.
I'd like to get a drive in the S2k and I'd say they aren't a car that you get right away, you need to grow into the frame of mind as they have to be caned and after driving anything else you aren't in that mindset, it's a bit un-natural, it takes time to get back into the classic VTEC mindset, more than Jethro would have had. My brother did want a 997 Carrera the S was a couple of year stepping stone originally, but he's not entirely sure now (after about 5 years) such is the bond he has formed with the S. It's never let him down, he looks after it (TGM are local to us and they are probably the best in the UK) and has had a little bit of paint done to keep it looking good. It seems to now be worth around 20k and going up.
Different proposition to my Chimaera as they were different buys, his brief was to find the best 55 plater he could, buy it and look after it well hoping to make a bit in 2/3 years to move to a 997. Mine was I found a cheap car (lack of funds but an oportunistic purchase I saw something in) that I could save, work on, improve and enjoy it for a long time. Both seem to have worked out well so far.
For the faults on the TVR as people always imply they are bad, most of that would seem to not really be true, the Rover V8 cars are OK (AJP and Speedsix cars are quite spendy) but like any 30 year old car there can be issues, some down to age some down to design/build and best to have it as car you don't depend on, although mine has given zero problems in the year I've had it, but I put that down to some things detailed below (a credit to the previous owner who was quite anal about doing the upgrades correctly).
The alarm/immobiliser is a post on the Chimp/Griff groups that does occur and because they were wired incorrectly from the factory, back in those days Meta who supplied the kit in anything from about 95 on had 2 relays the were two different rating in the immobiliser, one smaller one intended for fuel/ignition cut the other larger one for starter cut, TVR wired them around the wrong way causing the immobilisers to usually terminally crap themselves. I suspect that this was not the case for the early cars (up to 94) that had Foxguard kit and they were 2 relays rated the same, so at the change they just kept wiring as they had previously and a fault crept in. My car runs a modern system that has 2 relays of equal rating so it's not going to happen an easy replacement for £350, I don't know why people persist with the old kit when it first shows issues.
TVR also undersized the battery cables so that when warm it could cause a resistance in the cables and they couldn't crank the car, if left it will cool a little and the car will start. My car has had the cables replaced for something that sized for twice what's actually needed. Some cars have fitted what's called a hotstart fix, but this appears to be a bit of a bodge and just papers over the cracks, cable replacement is the way to go but it's more involved so doesn't get done often.
Distributors also wear out and there are substandard rotor arms and caps on the market, these along with failing ignition amplifiers and the stuff above would consitute the majority of breakdowns posted on the groups. As my car runs a distributorless wasted spark system with VW coilpacks none of this will ever happen on it. It is a lot of work though as it involves a new ECU and wiring loom too, which is 3k from a specialist. The modern ECU can also grab you about 30bhp extra and better drivability so you could view it as a bit of a bargain really if it fixes many issues and gets you more go.