The SSD will give you next to nothing when it comes to multitasking. Where it will shine is in starting applications and booting the OS.
In all the indepth tests I´ve seen, the HDD version outperforms the SSD on datatransfer where you transfer big files / a lot of data.
The main advantages of the SSD is the shorter boot, faster opening of most applications and the absolute silence.
Power consumption is marginally lower, overall system speed is marginally better and heat is also marginally lower. But none of these factors really justifies the added price if you don´t have an unlimited budget. (In which case you should choose the SSD just for the added durability a nonmoving storage solution will give you.)
-KJ
Oh believe me, multitasking has gotten crazy fast. If you try to load 2-5 apps at the same time, each application will slow down the other, thus creating the huge bottleneck which slows your mba to a crawl. Especially with a 4200rpm hdd.
Also even when your apps are fully loaded and if you do have a lot open and try to go back and forth the color wheel always comes up, not anymore with the SSD.
Anyway, when I put the intel x25-m SSD in my 2.53ghz mbp (and this is me coming 6 months ago from a 2.8ghz 8 core mac pro desktop, 16gb of ram, 150gb 10,000rpm raptor hdd) and this mbp + ssd is a bit faster.
Yes I said a bit faster, which is insane for a notebook vs. a desktop (in overall speed of the os, not like cpu rendering or anything of course against the 8 core beast). This goes to show that all this time the cpu architecture wasnt the one lagging behind, its the harddrive thats been the huge bottleneck for the past 5-7 years.
SSD upgrade has been the best upgrade I've ever made in the last 15 years 2nd next to 3d graphics, its that great. I cant wait for the mac pro desktop to get an update so I can pick one up and put my current intel x25-m in it, which would be even more amazing.