Peter, I doubt that new is bound to be better in general automotive terms these days, more so given the rate of technology alterations allowing glitches to creep in creating all sorts of issues, let alone the factory re-calls from many manufacturers..?
I suspect there is virtually no other car that can provide that which a Morgan can, may be one of the reasons I still have my old +8. That you have worked around your brake light issues, swapping your +8 may not be such a great idea. Also that you have the Merc for poor weather, extended trips, modern comfort levels and perhaps more mundane transport tasks, then you seem to have the best of both worlds..?
I have no payments other than running costs, for an Evoque, 991, and my +8, and in reality given my lack of usage, the Mog should have been sold some time back, but I just have not managed to get serious in doing so...I only use the 991 as I once did my Morgan.
I guess the fuel costs, green agenda, and the likely Baby Boomer effect on Morgan market values may add quite a bit to decision making, though I think the Russian war has perhaps put the green issues on the back foot somewhat, perhaps creating issues in the car and many other markets, which seem to be all over the place..?
As to the way that may all work out during the lifespan of the baby Boomers and the value their toys, perhaps the future benefits re the Tesla might not be as advantageous as imagined just a few months back..?
Good luck in your choices Peter.