The lithiums do not need more amps... although they can take it and not be damaged, unlike a SLA. So you usually see lithium chargers with more amps because, well why not?
The battery tender jr will charge a lithium battery no problem, just only to about 98-99% charge. I'd still suggest getting the charger made for the battery, unless the battery mfg says any SLA charger will work. The first thing they will ask if you have a battery issue is what charger are you using.
I'm not sure on the big battery tender, don't have one.