NRNB - What Does It Mean?

E. Without a doubt. It's a great concession.  Don't always have to take NRNB if you feel confident of a target, but why would you not want that bit of insurance as a saftey net. Road to Riches Gold Cup, Traffic Fluide Ryanair, MTOY Champion Hurdle are three I've done. I'll be all over Long Dog in the Bartlett NRNB too.

big fat capital A - not that i'm bitter or jealous

I'd say 'E' even though i don't have any NRNB. 'Any race' market is the bigger rip off, but nrnb  gives folk a fighting chance.

agree when i had it it was E - but make it pay - you wont have it forever

NRNB is feasible if one is a big hitter, the sp is small eg no more than 3/1 and/or many possible options likely eg Rsa, Ryanair, Cgc, etc; however, if only two options possible, any advantage gained if sp is greater is eroded by the exorbitant price paid eg ordinary sp is 10/1, nrnb is usually about 5/1; if so, wager a bet (equal amount or accordingly) on each, and lay it of at this platform closer the time or at its 1st opportune moment.