Omnia costs twice than Tocco but if you can't decide it means you can pay it. If you can pay it just do not think: buy Omnia.
It is not just a matter of CPU power, Windows Mobile is another world.
You will be able to do anything with it, almost like any Laptop.
For example you could install the best GPS naviagators all at a time like tomTom, iGo, Route66, Navigon, you are not limitated to Java (J2ME) games and navigators that takes data from the web each time you play them and it costs money.
Built-in WIFI and GPS are other great additional features compared with F480.
I like a lot the TVout feature. It gives you the chance to output your display over a bigger display screen when driving (lets say a car in-dash 7" display). Also you can play movies over your home TV screen.
With Windows Mobile you can play very advanced programs, running car diagnostics is another example.
Now some considerations NOT TO BUY Omnia:
A little bit bigger in size and weight, but still very very small.
Now a days a device of that category should have VGA screen (640x480), instead they enlarged the height from 320 to 400, so you get 400x240.
It is supposed to have same F480 camera witch is very very very bad (http://forum.gsmhosting.com/vbb/showthread.php?t=584891). Try to buy it where you can give it back in few days if you do not like it, so you can give camera a try.
Make sure it does not have the limitation of playing videos at 15 fps like F480.
Windows Mobile and apps written for it (it could include Samsung Touchwiz front end) use to be more unstable and buggy compared with propietary SO (like F480). Resetting a WM device is considered very common practice. People having a WM devide like to have reset button very accesible.
Once you discover all you can do with Windows Mobile maybe you will spent with it more time than you have
In my particualr case once having my F480 for a couple of days I liked it so much that I was going to sell it...to buy Omnia!!!
But tha was just until I discovered how bad the camera is