It would be about an even trade imo but the treo has a lot of age on it and cost more to recone, maybe 5years ago it would be a good trade but I would imagine the soft parts are at the end of their life due to age.
I understand what your saying I have been doing this for a minute and know what impedance rise is. You will understand better on what im talking about when you clamp your gear at different ohms.
Your electrical should be good with what you listed.
I would gain match each at .5 if they were mine (less issues and if something happens you don't risk losing 2 amps when strapped) but if you feel the need to strap do it at 2ohm imo, you really won't notice the difference in daily use
Lithium Batts are very customizable from charge rates, discharge rate,low/high voltage safety depending on the controller used unlike agm or lead acid it only defies the laws of dumbazz