F3's aren't even remotely close to the speed of SSD's, sequential writes, maybe, but sequential reads and writes are the single least common situation for hard drives/systems to be in.
Sequential speeds aren't even useful for game loading or installing, that will largely be random reads/writes, sequential speeds generally only crop up when unrar'ing large files, or moving large files around, two things you generally avoid on SSD's anyway. In terms of small random read and writes, which is the majority of what a PC does when loading apps, games, booting and installing programs, a SSD is in the realm of 20-50x faster with immensely higher IOPs in all situations which is immensely useful when multitasking.
A random 4kb read on a F3 will be around 0.3-0.5mb's, a cheaper Indilinx drive will offer somewhere between 20-30mb/s for the same type of reads and those are the situations where the system hangs, or slows down, you're transfering a file to another drive and open up photoshop or firefox and it hangs and takes ages to sort it out, on a SSD its instant.
But people need to realise, you'll gain fairly little in terms of game loading, because the CPu and GPU do a lot of work uncompressing data and sorting things out, though some games will load noticeably faster.
Theres fairly little need to have a massive number of games on your SSD, most won't show any difference in loading times between the OS being on an SSD and games being on it, or the games being installed to an el cheapo massive drive.
LIkewise people can show a massive difference between the £300 and £100 ssd, in benchmarks, in real world usage you could barely tell the difference. any half decent ssd will give you the "instant" feel to app loading, stop the system dragging to a halt when multitasking, sorting out most things. You can install a few hdd hog games on your SSD, the few games that are better on an SSD or have a huge amount of loading(some MMO's) and stick the rest of your games on a secondary drive.
Its well worth the cost.