Is it worth using a RAID with SSDs?
In general: yes. For data redundancy, RAID 1 or greater is the way to go. Now, with SSDs, I'm not sure how this affects their performance but I can't imagine it being too detrimental. I don't have experience with SSDs so I can't speak to it.
It seems like the major cause of
mehanical failure will have been
eliminated by using the SSD
Logically, yeah. But some people are reporting performance problems with SSDs over time. Basically SSDs are still not 100% mature for the consumer market IMO. I can't wait for the technology to mature but when you have problems like this from Intel, and performance degradation it's only a matter of time until manufacturers work out the kinks an outmatch their lowly "disk"-based hard drives.
.. so you're basically trading "Chance of SSD failure" for "chance of cheapo motherboard raid controller failure".
Good point, but cheapo motherboard raid controllers affect both SSD and HDD so it's really a matter of the hardware RAID.
I'm not sure if that's worth it.
Now we get to the meat of your question. Are SSDs worth the money? For speed, without a doubt I think they're worth it. Unless you want a WD Raptor at 10,000rpm, SSD is so much faster. But you said...
I'm worried about the drive having
some sort of mechanical failure and
losing my data.
I think it's safe to say, just wait. Wait for at least 12-18 months until the manufacturers mature their product lines, prices come down, capacity increases, etc. etc. There's no harm in waiting in the computer industry. Your emphasis is on data redundancy, not speed. Why risk it? And the disks today are so cheap and offer more capacity, if you absolutely need storage today, get cheaper SATA II HDDs and hardware RAID them. You'll probably spend less money overall and when the time comes for SSD, you'll already have a good RAID controller (assuming you put the money into it).