@Tobei, I would only mood +Def if you run prompt healing/shield mysteries to essentially stop blitz teams killing your roshi by r2 mystery, or even r1.

*There are also some ninja standards/skill sets that "the skill is not subject to the opponent's defensive skills" rendering a higher DEF less useful than HP in this case

Otherwise in most of scenarios +HP works safely with Roshi. HP scales the best with most ninjas, you get the most out of that 65%.

I would only mood Roshi to +Nin if my BP is among the top 0.1% of players (or top few in your space-time cluster) when 99% of your PVP fights are against players a chunk of BP lower than you. You mood Roshi on +HP/DEF to the point where it unkillable vs the worse blitz scenario. When you can achieve that, you can mood Roshi to whatever you want to.

Bit off topic but i'm speaking from experience still using blitz with Light Main (41k BP main) in version 4.0, and very easily managing PVP events (i.e. top in Sage field, 5 win streak in Mats, 90% win rate in Bonds, Space top 2-8). There's only 1 player's Roshi in my PVP cluster that I can't beat due to his +60k team BP over mine. Other Roshi's at similar BP or even 10-20k higher team BP are no trouble to blitz. Perhaps also because Roshi is earth element weak to light.

^+1, +HP/-Atk all the way. Roshi's also one of those ninjas you want to invest a bit in and 65% it. It'll pay off in the long run I can vouch for it.