If you can find one, the 09 Riots are superb. They come in either a wenge or maple burl top with a satin finish. They're neck thru with a string thru or top loadable bridge with emg-hz pickups. They also sound amazing.
The 2010 riots are basically the same, except for the woods/finishes. The '10s have high gloss finishes in brown, cherry and I want to say blue. These too are top notch.
Sadly it seems the Riot was turned into a budget model for 2011 but I haven't had the chance to play one. All I know is the 2011s are bolt-ons with a cheaper looking bridge and Schecter pickups. Also, the finishes are kinda boring, with solid high-gloss black and a high-gloss metallic (glittery) blue. Despite those changes, however, it may still be a pretty bangin' bass.
As for the basses you mentioned, of the Stiletto models availble, my favorites are the Studio (of which I own a 6-string) or the Elite (soooo pretty, with all the goodness of a neck-thru Stiletto). Though maybe I just have a neck-thru bias

(although, the Custom is so damn pretty I can get over the bolt-on neck).
Unfortunately, I too have never seen or played an Omen in person.