Hmm. I own several Omega natos and dozens of natos from other producers, and the only ones that come particularly close to Omega in terms of comfort (*of what I own) is Crown and Buckle. I find the crown and buckle natos too flimsy, which allows the watch to flop around a bit more than I like.
That said I DO agree that the way to go with the PO if you don't want it on the bracelet, is to go with it on a rubber strap.
As far as the 300 goes - I own a summer blue heritage and love it pretty much any which way.