It would be interesting to test and compare all these.
Dont forget that these Amass are like "inrunner" and the regular Xt150 are "outrunner".. i mean the outrunner type have larger diameter where the contact is made
= more surface. But it would be interesting to test test these.
I use the XT150 and also the 10mm bullet connectors and these work great..
but the problem is HOW PEOPLE SOLDER THEM
witch become sometime MORE IMPORTANT than the contact resistance themself...
If only making a bath of solder in the cup and drop the strands into it.. it give VERY poor result..
Problem is that people think that solder is a good conductor as copper or silver..
witch is way far from that!
Personally what i do is to take all strands of the wire and make a kind of mushroom shape with thesse to match all the inner surface of the contact cup o fthe XT150 and the 10mm bullet... then i apply flux and then solder and finally remove the excess flux.
This way the resistance between the wire and the contact pin is way less and you get less heat!..
but about the contact itself it also depend on how their spring effect is preserved.. Personally i bend all these a bit to have them VERY tight in the contact.
Strangely.. on E-S i'm sure we will still see people with these Amass connectors and use solderless battery pack design