I can only tell you about my personal experience since I have both 5070G and 5970R…
I also started with 5070 many years ago and I was in love with it : a very oversized classy chronograph with some vintage and modern look at the same time, the ultimate sport chic watch imho (5740 is certainly a good contender but obviously there are no vintage touch at all and I love it). You get it I love this reference, 5070 has so much charm in addition to beauty! And in spite of this true love I had to let it go for funding a very special watch that I didn’t want to miss as it is so special to me and a particularly exceptional example (I am talking about my Wonder Watch, the ones who know me well here know that I am talking about my 3448). Since that day I know that I would acquire a 5070 again as I was missing it a lot. I certainly don’t regret my Wonder Watch but promised myself I would get another 5070.
In the meantime I had the opportunity to acquire a 5970R ; it has been a grail for me since ages and once I had the opportunity I pulled the trigger immediately as you can imagine. I wear it quite often, it’s a fantastic watch so easy to set (as it was rightly mentioned by patekova) and it’s pure Patek DNA. If you have a chance to acquire a 5970 in any colour do not hesitate, each of the four is having its charm (J rare, R flamboyant, G versatile, P ultimate). But even if 5970 is amazing and another league, the look is totally different and I was still thinking of my former 5070. So when I had the opportunity to acquire a 5070G freshly serviced by PP last year I couldn’t resist and fulfilled my promise to myself. I am now the happy owner of both 5970R and 5070G (in addition to my Wonder Watch in J) and so happy to have such a trio in the 3 metals for completing each other perfectly. Btw please don’t rank them on a podium I am equally happy with the 3 of them, they are so different.
What I mean is don’t think in terms of value or whatever other criteria but exclusively love and passion to take your decision. 5970 is fantastic but 5070 also, so take the time to decide: will you miss more the 5970 that you didn’t get or the 5070 that you had but no more… Once you are positive about the reply you are ready 😉.
My two cents…