Difficulty of 4 man HU SNGs

Hello,
Long time reader, first time poster.

I have been grinding the 4 person HU SnGs for some time now and have maintained a 55% win rate over roughly 100 SnGs. I have recently moved into the $20 SnGs and have won 2 of 5, with 2 losses being part of my bad losing streak for the past week where I couldn't win a 75%+ favorite hand.

My question is in regards to the $31+ SnGs, what is the difficulty level and does or has anyone attempted to grind them full time? If so, what results did you find in regards to opponent skill and difficulty compared to lower stakes?

I don't play the $30s yet but from everyone that I have spoken to about the HUSNG world. They have stated that its best to grind where you are comfortable and when your ready to move up, you will. At these stakes its more important to get your game down and your head leveled.

To respond to your question directly. I couldn't imagine the 30s being more difficult than the 20s or the 10s. I've even heard some regs say that the opponents you face dont even really improve until the 100s. Again, I havent played this high. Just passing on info from when I had these same q's.