The SL25 is not prone to cracking. I have had one go but thats it. No other disc rim with an ERD of 590mm so your out of luck there. The current forza is the replacement ERD 591mm so there you go.
If I ever need to replace the rim. Is there the option for going for something with a slightly shorter ERD (XR31T) and having the spokes cut shirter and re-rolled?
Yes you can get spokes shortened; I got some CX Rays done when I swapped an Open Pro for Kinlin and like fuck was I throwing them in the bin! George Hall Cycles did mine
The SL25 is not prone to cracking. I have had one go but thats it. No other disc rim with an ERD of 590mm so your out of luck there. The current forza is the replacement ERD 591mm so there you go.