it's not an opinion, we see about 1-2 per month,
'HELP!!! my raid0 failed, how do i recover it?',
first question we ask is
'do you have backup from the day before?'
the answer is inevitably
'I don't have any backups',
the only answer is that point is
'reinstall windows start from scratch'. Whilst this is the same as normal, the risk is probably more than twice that of normal, if either disk fails you lose everything, if there is a glitch that puts the disks out of sink (power failure) you lose everything.
I knew the risks, I lost an installation. You don't know the risks, it's fiddly to get from a non-raid installation to a raid installation. with respect you've not done the 2s google search on raid0.
This isn't a fixed 'opinion' this is the collective bitter experience. Using raid0 for a heavily backedup system for speed, using raid0 for scratch space for highly temporary files that you don't mind losing, these are good uses. It used to be used for speed, with an SSD it's no longer needed for that reason. Windows can merge disks in a less risky way (JBOD) but not the OS disk,so you could have a small OS disk and then jbod the two 256's together, less risky, but difficult to restore from a backup.
There are 10's of consequences to what you are considering, we cannot and should not decide if that risk is acceptable, only you can do that once you understand those consequences.
get a 500Gb is easiest, put the OS and certain types of programs on the 256, games on the 500 perhaps, being structured about where you install will help.