What would upgrading get you.. Depends on your battery bank.
Proper converter size is about 30% of Battery C/20 so for a single pair of GC-2 (220 amp hours at C/20) that would be 66 amps.. So a 70 amp converter is good (you will likely suck 4 amps for parasitic loads) but upping to 80 may (Or not) fast charge your batteries leading to shorter life.
The other factors to consider are the wires.. IF you increase the size of the converter. the increase may be "Eaten" by long wires between the converter an d the battery so you'd get only 1 or 2 amps improvement.
In an ideal world.. it would take a bit of time off re-charge when boodockign. perhaps 20 minutes tops (80 amp) not really worth the upgrade.