Yes one pair of GC2 golf cart batteries WILL give you more Ahr capacity than two group 27.
Group 27 will give you at best 80Ahr each so a pair of group 27 gives you max of 160 Ahr. However, that 80Ahr is if you ran them 100% flat.. Which will kill the capacity in a matter of a couple cycles. Basically, you would only want to take a max of 20% out of group 27 and with two that means you get 32Ahr to work with.
The lowest rated GC2s would be 210Ahr and with GC2s you can easily extract 50% of the capacity and not harm the battery so you could easily use 105 Ahr.. GC2s can also be drawn even lower than 50%, you can extract up to 80% which is what the manufacturers use to rate the amount of charge/discharge cycles at..
Don't do that to group 27s..
And yes, I use one pair of GC2s to power my home fridge conversion, I have no issue going 24 hrs without the need of recharging. Add some solar panels and I could easily make a long weekend without the need to run a gen.
