I've got my V6 on Classic Car Insurance and this helps with costs. If I remember, when I had my GTV TS, that was also on Classic Car Insurance and there wasn't a massive difference. I think I paid about £700 all in for the two.
If you're a dab hand with the spanners, you can reduce costs that goes without saying. The V6 Front Suspension is likely to wear quicker given the lump up top. However in my experience there are age related things such as oil coolers, clutch slave cylinders, corrosion, exhaust leaks and brake lines. A lot of this stuff would be things I would be looking to have been done when you're searching given that most of the fleet is likely 15 or more years old. In another sense though, I've enjoyed getting to know my GTV V6, repairing it and bringing it back to life. The only thing that annoyed me was the rusty sills as I couldn't repair that but all good now!
It doesn't get mentioned much because of the engine but one thing I really do prefer about the V6 is the gearbox. I find it much smoother and effortless. It's a treat to drive and operate. However for winding roads the TS gearbox is probably a little more engaging.
They're both great cars in my opinion. I loved taking my TS on the meandering country bends and weekends away. I felt like I could drive the TS without things ever getting hairy; pushing it a bit more in other words. The GTV V6 is a little less forgiving and the handling is not as sharp but it just wants to go. A full freshen up of the suspension, Q2, polybushing and some ARB upgrades are worthy upgrades.
I've been without my GTV TS for around 4 months now and I replaced it with a 156 2.5 V6 and I think that I will probably revert back to a TS one day. It is more fun than the 156 for me; simple as that. I grew a bit tired of the silver colour in truth. However, the GTV V6 is something else. Money just doesn't even come into the equation with that car.
I live in Sipson right outside Heathrow - my GTV is in the garage at the moment but I would happily take you to see it, tell you everything I have had done to it, costs etc. Don't have the TS anymore but can certainly help out.