I've done some "academic" tests with a STEC Mach8 IOPS Flash Disk and Opensolaris SNV_134
The test included measuring installation time (from USB Image), first boot time (importing SMF manifests takes time), and normal boot time (both after GRUB Menu until login screen).
The test was done on a Intel Core 2 Duo @ 2.4GHz Laptop and as a comparison on a EeePC 1000H with an Intel Atom CPU.
The Flashdisk was recognized immediatly:
Here are the measured times on my Core 2 Duo system:
First boot: 3'22''
Normal boot: 30''
Here are times for the EeePC with Atom CPU with SSD:
First boot: 3'50''
Normal boot: 54''
Normal boot time for EeePC with Atom CPU with Harddisk and OS 2009.06:
Normal boot: 1'25''
Opinion: Don't waste your money on an expensive SSD if your overall system is slowish. For comparison, the Atom boot time is only marginally better with SSD than with a HardDisk.
On a faster system, you get much more out of a Flashdisk. Remember that (Open-)Solaris was never the fastest system to boot, but I think 30s is a quite good achievement.