Update
FYI, I purchased both SSDs from apple (pre-installed, BTO system). I went ahead and did the RAID 0 setup as instructed in the Apple support pages. My system info now says: "TRIM Support: Yes" for both drives while they are in RAID 0. I don't know whether TRIM is truly enabled or just "supported."
My research did yield that Intel enabled TRIM for SSDs in RAID 0 for their recent desktop 7 series chipsets. The mac mini has HM77 (Mobile version of the 7 series chipset). Since the RAID via Disk Utility is software based, I don't think this is relevant. Would have been nice if apple used the built-in hardware RAID.
I am aware of the data loss potential. I have a synology DS412+ NAS for data, synology DX213 (4TB) for local backup, and Amazon glacier for off-site back up.