Demasting is still a problem and I think 30% is perfect to keep players fighting side to side and not sails all the time. I had a fight in my Consti vs 2 Frigates. I was able to keep them off and enjoyed the fight up until they chewed my sails and fun was over. I had their armor down low, but I had no sails left to operate the 4th rate. This 30% is what I needed to keep fighting, it really works well in gank situations and will help many players.
You are on the right track and if someone says it's too much I say it's not enough. Gank demasting is what is killing this game, making demast useless what you should do. Players should fight broadside to broadside. On the other hand, Demast in port battles will still work, since incoming damage is 10x heavier.