I would almost think /nin would be "safer" since SCH has SS natively now. However my concern for subbing nin would be you wouldnt have diaga so you would need to always make sure you have a strat up for manifestation to clear blink.
I would imagine you shouldnt have trouble landing bind at 99 but blink could def screw you if it absorbs a bind. Even at 99 seriyu still hits fairly hard and his TP moves are still fairly potent.
Phalanx and FC will prove invaluable in such a situation, which is why I suggested /RDM over /NIN.
You can get their swings down pretty low at this point, particularly on jobs with enhancing skill.