I find my 34C pretty mild - a lot milder than the 3 Gillette Rockets I have. The other non adjustables in my stable are an old 7 o'clock open comb (aggressive) and an old Empire No.2 - it's aggressive enough to fight off Chuck Norris!
I agree with some of the other comments about different people having different experiences. I find the Derby and Astra blades to be pretty rough. Quite like the Merkur blades which other people find pretty poor. It's all horses for courses.
I find that with the 34C loaded up with a 7 o'clock super sharp blade, it can be quite mild and smooth. So much in fact, that with a good soap, it can be too smooth on the third pass. I found this the other day with the new Empire Soap from Squadron. It was just too slick. Perfectly good for a straight but not the 34C.