When replacing a bank of 6 sealed leisure batteries a few years ago, I was considering Trojan, crown, and another make I can't remember. The original set up was 3 pairs in parallel (I'm on 24v) so I was looking at 4
6v in series, the cost was best part of a grand for the tall 460 Ah types.
For half this figure, I bought a nearly new forklift battery, complete, the tank,cells, New interconnects, everything. I have plenty of height above for these tall cells, in fact the steel tank sits on the base plate in the engine room, the deck plates cut to fit round it. It makes a handy seat too, and helps balance the offset engine.
The footprint is smaller, as they are taller, 500 mm high.
Another advantage is the cells can be individually replaced should one die.
If you have the headroom, it's worth considering.
After 3 years they continue to perform well. As a test I sometimes put the immersion heater on and watch the voltage drop. On Friday, I did just this, heating the calorifier in 45 mins. The load is 63A. Voltage dropped to 24.5 on load, then recovered to 25.4 after heater cut out.
So I think there ok!
Couldn't do this with the original sealed batteries. Inverter shutdown on low voltage after about 10 mins..