Greetings WC! Happy New Year.

There are slim-pickin's on upgrade/mod info for the XRBs. Search and dig through the forums you may find something related. I will try to find links that I once visited that had battery info. I was considering the same things since the addition Hirobo batteries are pricey. Hirobo seems to almost exclusively use the connector they use, but I know it is not a proprietary type. I just ended up giving up the search because of the fear for damaging the lipo's, the charger or the heli electronics. Too me the cost of replacemnet keeps me cautious.

In any case good luck and i will post the links as soon as I find them.

Cheers!