I bought a 164 for my first rep a few weeks back and it's away for servicing right now. If you look after an A7750 movement then there's no reason it shouldn't last you a long time from what I've read. They're just usually not very clean/oiled/well assembled from the 'factory' is all and there's more stuff to potentially go wrong than with the A6497.
There's an
interesting thread here with a watchmaker's point of view about certain kinds of reps (including PAMS with A7750, chrono & secs @ 9 [164] and PAMS with A6497/8 [390]).
Personally I knew I wanted the 164 before I had any idea what kind of movement was inside it and before finding out how well repped it was, I simply wanted one because it was the PAM that first made me fall in love with PAMs when I saw one in a display case, if and when I ever buy a gen it'll probably be the 164 for this very reason, regardless of how good a copy the rep is.
With hindsight it may have had more to do with the beautiful brown alligator strap it comes on and the general luminor stylings of the watch than anything specifically to do with the 164 itself but there you go, I'm sure there's going to be a big box of reps in the top of my wardrobe soon (I just bought a very nice 243 m2m and already serviced which I'm wearing right now and I've got my eyes on a 000, 448, 292, 351 and 113 already) but if there's ever a gen hidden away in that box of reps it'll definitely be a 164.
Long story short, both watches are very well repped. Personally I'd just go for whichever watch you like best and if you're worried about the A7750 movement then simply bear the extra expense and get it serviced. My 164 cost £260 including WU fees and delivery, £110 to get serviced and if I choose to replace the poorly repped alligator strap with a real one at some point it'll probably cost me another £150 or so. In total that means I'll have paid (actually my wife will have paid as it's a gift) £520-ish for a near perfect and very reliable copy of a £5100 watch. I'm more than happy to pay 10% of the gen price-tag for a watch that I'll enjoy every day.
Or you could just buy both LOL, you know you'll end up with both of them in the end and it'll save on postage, or at least that's what I'd tell myself...
