We've just started rolling out a few SAS SSDs to our HPE servers.
In theory there is no problem with using them in RAID5, although in reality depending on your use case, you may just be better with a pair of big drives in RAID1, as even standard 6G SATA SSD drives will easily max out gigabit connections, so if you are looking for transfer rate improvements (rather than just random I/O) then you will need to look at 2.5Gb/5Gb/10Gb/25Gb+ ethernet if you haven't already
Both RAID1 and RAID5 will wear all of the drives out at a similar rate, so ideally I would allow for a cold spare drive either now, or in a few months time and then swap that in to avoid all of the drives failing at the same time due to wear (although you should be able to gauge wear via the RAID controller software).
It's worth looking on ebay / specialist enterprise I.T. brokers as you can often get several used but low wear enterprise drives, for the cost of a single New drive.