Good pointers for you there Pat.
A lot of these 'jumper packs' use buck/boost circuitry to provide charging and regulation, usually from the cheapest supplier possible. Those circuits can be the worst noise emitters ever!!
As Martin says, good for it's intended purpose but not much good for radio.
I'd be wary of something with an LCD interface/display too as they usually bolt on the cheapest processor, also producing RF hash.
But as mentioned, some people have found units that can be worked with successfully. Often the problem can be trying to get an identical unit because although they'll look the same on the outside, the circuitry inside can be different.
All a bit of a gamble in my eyes
Does no one use ordinary lead acid cells anymore? Flip, they were way easier to use and charge even in the field!
I suppose once you find a decent DX hill you don't want to be lugging along 200Ahr lead batteries or operating QRP......
Anyway, all good stuff.