Which mfgr LFP123 are you using (SF) ?
I've been using K2 Energy LFP123A cells for >5 years now with good results. I believe K2 sort of specializes in LFP. They're not that widely available, so I'll mention that they appear to be in stock at batteriesinaflash, where I have purchased them previously. K2 has a proper data sheet for them, which I had K2 send to me. I tried unsuccessfully to attach it here, but failed (it's .pdf format), but I just did a crummy screenshot of it and will try attaching that below. If that doesn't work &/or you'd like the proper file, PM an address to me and I'll gladly shoot that file over to you. I also use these in other EDIT: LED
lights (besides the 1L1AA) which are designed specifically for 1xCR123A cells. As stated, I use them in the 1L1AA because it provides far better output (per SL specifications) w/3V than w/1.5V, so why not?
I have some others from Tenergy, but have never used them because I'm not crazy about their stuff, and also can find no proper specs for them, so when I found the K2s after I ordered those, the Tenergys stayed in the wrapper unused. They might be OK, but I believe they are of lower capacity as I recall (besides lacking complete specs). I'll test them some time when I get around to it just to see how they work in case the K2s become unavailable at some point.
For the average bear I might suggest the SF cells, although I've never used them and don't have good specs for them either. They're probably more widely available (and like K2 have an available 2-slot charger for those who need that), and what they do have is a very well-known, established, and highly respected name on the label (which has value also), and I'm sure SF did proper due diligence and qualification of them before putting their good name on them. They have a lower capacity rating than the K2s, but I'm fairly confident they would work well, and would likely buy them myself if I needed more and couldn't get the K2s.