I certainly have not heard of any recurring gearbox problems in an Elan gearbox. It is made by Ford, of course. As is the short block of the motor (although the crank rods and pistons are not used in non lotos applications, and the block is Lotus only from 1967. The differential internals are Ford.
English Fords are reliable.
Things like suspension bushings have a pretty short life in a Lotus. They are small and highly loaded. The rotoflex couplings are notorious, but I never had to change one, except in my BMW 2002.
The water pump is hard to change(like pull the engine hard to change), and is known to fail. I had a spare, but never needed it. All the elans I have had had at least 1 slow to nearly dead electric window, but they never stopped working. The instruments are Smiths, so we know that they are inaccurate when they work at all, but that doesn't slow you down.
Chassis rust is the biggest problem with them, then chassis damage. Rear wheel bearings are known to be a pain, but again, I never had a problem with it.
I drove mine all over Alaska, but not in the real cold winter. I did get cought out and had to drive it in snow a bunch of times though.
The +2 is very comfey and refined. The roadster is, too. Excellent suspension compliance. I would rather have one than my Lotus 7.
They are still quicker and better handling than a Miata. Chriss Beebe bought my last one, he flew out to Oregon, then drove it back to Madison. He ranit between 70 and 80, and averaged over 30 MPG. It suffer a seized brake calliper on the trip, but that is not unusual in an old car which has fallen into disuse.
With new bushings in the suspension, including the diff mounts, new motor mounts, and a new water pump, it should be good for lots of miles.
If you expect it to work like a modern appliance, you will be disappointed. If you expect to do some maintenance and use the car, it should be suitable. If you buy one with a bunch of needs, and expect to drive it every day, it probably won't work out well either. You need to start with a solid well maintained not worn out car if you expect to use it for regular transportation.