I do Andy ! (as you probably know)
I have not made the switch to LiFePo yet … since I can get lots of old laptop batteries for free, and most of those still contain Li-Ion technology.
My battery packs are home made, with balancing leads for the charger, and a polyfuse and PowerPoles for the output.
I do have an iMax B6 charger, but it’s a bit too heavy for travel, so I have this little charger:
It works from a 9-16V input, so I can use it with a wallwart, in the car, from a solar panel …
and most important, I can’t forget how to use it, there are no buttons 
It can only slowly charge via the balanceing lead, but I like it better … there is probably less fire hazard.
(search your favourite shop for “BC-4S15D” charger)
For testing, selecting and matching the good cells, I have a Liitokala Lii500 charger (search your favourite shop for that name). It can charge and discharge 4 cells at a time, and measure their capacity. For a similar device for LiFePo, see post above from MX0IDX.
Backup solution is the powerbank trick, with a seperate cell holder, as discussed several times before on the reflector.
See an example in this SOTA News (scroll down to " Airport security and batteries"):
73,
Luc ON7DQ