A friend has an R-75, it seems to be pretty much the equal to the R71A without the "senior citizen" worries, as the first R71As are pushing 30 years old. I had an R70 for a short time, and the lack of a keypad made me sell it off. Not bad at all though.
I don't have my NRD-515 anymore, I had a cash flow issue and it more than paid my mortgage for a month when I sold it, but I really miss it. It was a "Gilfer" modded (and other mods too, I don't know who did them) one, with the knobpot added by Universal in place of the delta tune (The detent on it was annoying, and it was too coarse for digital modes anyway). It was super quiet and with an old speaker I found in my basement, it sounded great in SSB modes, but still wooly in AM.
I still have my NRD-525, an R-1000 that's almost mint, a couple of FRG-7s (One looks brand new, the other not so nice, but both work great), two R71as, one is dead, I'm not sure what happened to it. The PS failed almost as soon as I got it, but it worked on 12V, for a while, then it popped loudly and died. I think I'm going to just sell it on Ebay for a parts radio, as I don't think it's worth the time and $$ to fix it. The other one has one of the replacement memory boards in it that wont lose everything if the battery dies, and an audio mod that solves almost every complaint I've had about the way an R71A sounds. It's just a couple of resistors, but you have to take a PC board out to do it. That one's had all the caps changed out and a previous owner put a fan on it, the top of the case had slots cut into it and it was done perfectly. The fan really does a good job of keeping it cool on 115V. The fan is a good one, very quiet, about 4" in diameter. Even running as slow as it will go will keep the radio pretty cool. It has a built in pot to vary the speed, and even on high, it's not that bad. Getting back on subject, I would say the R70 is a couple of notches better than the R-1000, mostly in stability and filtering. The R-1000 does sound better though.