Most kind.
@Rusty Bojangles - important is WHERE in OZ? - The colder part or warmer part. It need not be subzero - sub 6 or 7° can be enough to peeve one.
If you are NOT in the always warm bit then I would suggest that it is better really to have an AGM and carry a small lithium booster pack in your jacket pocket.
If you are indeed always in the warm bit - then go for Lithium as they will not dry out. All lead/acid batteries do eventually - even "sealed" ones.
There is always a trade off somewhere though - and the overall capacity of most Li is lower.
Most 20aH lead/acid replacements are about 7-8aH.
So you can run a Li down really fast if the engine is not recharging. The plus is that they tend to also recharge faster because they're smaller.
The Chemistry of Li means that if you are running something that does not need much current (an amp say) - Li are really good at keeping volts high. So you may not realise that it's near empty until it's really near empty. Lead Acids will tend to pump out amps at the expense of volts - this usually is more detectable before it is too late.
I'd suggest NOT wiring any accessories to an R3 battery that is on when the engine is not - lead/acid or Li - The battery is basically on the limit for a 2300cc engine. I have one twice the size in my 1979 Guzzi.
Get a proper battery tender rather than jumping - esp on smaller batteries. 20aH is not BIG.