Regarding the rapids, I have heard that many times before and indeed it was one thing I said. I will ask you again in a years time and more than likely you will have changed your stance
Rapids are nice to have but a more important thing however in my opinion is acceleration.
With the size of steppers you are considering I would think 1:1, 1.5:1 or even 2:1 would be a better choice. As mentioned I had 916 OzIn (6.4Nm) steppers on the Bridgeport geared 2:1 (manual conversion) and 2.5:1 (Boss 6.1 conversion) and there was more than enough torque. I was actually considering making them 1:1 but then decided to go with servos instead as using the Bridgeport after using the Beaver NC5, which had servos, was a chore.
As for the motors lasting longer with higher gearing, I dont think that will make any difference to them, I ran the Bridgeport almost daily for 4 or 5 years and there was not an issue. I still have the geckos and motors here, just have to find something that I can fit them to, was going to put them on the wee lathe but decided to go servos on that as well, maybe another coil winder would be a good idea, one made specifically to wind small spools of Alu wire for the mig's spool on gun
Hood