SSDs are not "marginally faster" - indeed, it's not even a straight "X% faster under Y conditions".
A hard drive is made of spinning magnetic platters. If you want to read something on the other side of the disk, that platter has to physically spin. Disk read lag is measured in milliseconds, and that adds up for every file - SSDs have no moving parts. Much like RAM, accessing a random byte is no slower or faster than accessing any other random byte. Even if an SSD's read and write speed wasn't on the order of 10 or 20 times that (depending on model) of a standard drive, the responsiveness of not having read lag would help.
Personally, I would never run RAID 0 for SSDs, but then, I wouldn't do it for HDDs either. SSDs effectively only die through extreme force, or wear (And for modern SSDs that wear is measured in decades, rather than years), wheras there's a *lot* more to go wrong on a HDD. Moving parts are not the future, solid state is.
Umm, not quite. Every time you write to an SSD, or a thumb drive, you are causing atomic level degradation of one of the layers in the NAND gates that make up flash memory. This is an unavoidable effect of state switching. And those gates =will= fail in time. The big questions with SSD's atm is exactly how long it will actually take in real world environments, and how well current software can deal with bit failure. And while you may not have a spindle to bend, or a read/write head to crash, you still are dealing with IC chips soldered onto a multi-layered pc board. One good impact can break a cold solder joint and kill a SSD just like it can a mechanical drive. And unless the SSD is hermetically sealed, the mounting board is still vulnerable to airborne solvents. Weaken the glue holding the layers, and poof (and we won't even try and get into atomicity and drifting cell charges.....). Never mind that SSD's are a bit more vulnerable to electrostatic damage than HDD's are.
And while RAID 0 has exactly -no- fault tolerance, it does almost double the read/write bandwidth your hard drive array has available. That lack of fault tolerance is why it is never recommended for mission critical application; RAID 5 or 10 usually gets that nod. But many of the larger SATA II SSD's are actually configured internally as RAID 0; this is safer due to the fact that there is no FAT table needed to spot data. By the very fact that the SSD has unchanging data locations in the chips, you can easily wire it to address sequential chips in a striped pattern, doubling your bandwidth (which is why this is seen in SATA II drives).