The 2 bank chargers I had on my last 2 boats were BPS models and they worked fine for a long time. However it said you could not mix type of batteries. It had a single setting for either lead acid or GEL Always wondered why, but I think after reading this I know why.
On a side note. I went to a smaller boat last year and only have a single Cranking/Trolling combo GEL battery. I have an 8 amp"Smart" charger and it apparently adjusts internally because it has no setting for type battery. Manual just states it works for all type 12 volt batteries. Been fine for the last few months at least.
Mark 1:17 ...I will make you fishers of men