If one must stay and one must go, myself, I'd keep the 701.
There are always a fair number of Duals available locally where I live but few are direct drive. Of those, 701's seem to sell the fastest and go for a pretty good buck. So maybe one can consider them a better investment from an appreciation stand point.
I have multiple turntables including a 701 and a couple of years ago, got a 721. It was an opportunity buy and of interest only because some opinions I read said it was Dual's best ever turntable. Alternating between the two, it did not really strike me as superlative. I found the 701 to have a better tactile feel to it, felt more substantial and frankly, thought it was better looking. Intangible, but I get satisfaction from owning Dual's first direct drive and that it's motor was unique for the time. I gave away the 721.
My first good turntable was bought new in 1968 and it was a Dual so I've been an aficionado ever since. My mother would take me along when she went looking at console stereos in department stores but if it did not contain a Dual, I told her it wasn't very good. She was basically just furniture shopping. Not that I've never strayed but I can't keep away from Duals.
My total turntable tally is nine, four of which are Duals. Since I think having nine turntables is silly, I am often thinking which to keep. Three seems a comfortable number but which two would be best company for the 701? I really like the original version 1009 I got last June (I've been using it-almost exclusively since then) but I also like my original version 1015 because that's the model I got in 1968. The 1015F is good too, it's been my 78 & 7" 45 player for the last couple of years - stacking spindles included.
But then, I really like the looks of my Garrard Zero 100's. Also, the looks of my fully manual and fully automatic Toshiba direct drives. Those have standardized headshells which is a nice break from cartridge sleds. I also have a silly number of cartridges.
The two I would have the least problem relinquishing are a semi-auto direct drive JVC and a fully auto belt drive CEC.
But I digress. Your choice is easier - keep the 701. If for no other reason than it's more historic.