Josko,
But I have been using a 10 wt. since I started SW FFing almost 30 years ago.
Thats it - no 7, 8 or 9 wt. Thats not to say you can't make use of the lighter weight rods under certain conditions. Its just that I've never encountered a situation that I felt a lighter rod would be BETTER.
I think I also told you previously that I tied my 20# leader on to an immovable object and tried to break it by pulling on the rod and palming the spool. I couldn't - even with a knot in the leader. It gives you some idea how much pressure you really can put on a fish.
I think Lefty recommends a light drag because you can always apply more pressure if needed by palming. By the same token you can relieve the pressure instantly.
You can also vary the amount of drag by changing the rod angle and fingering the backing against the grip(not with gel spun backing).
Even with a 10 wt. a 25 - 30# fish is going to bend that rod so its as straight as a string.
If your in a rocky area with big fish present you might want to consider using a 40-50# shocker ( 10-12") to take up some of the abuse.
MAybe you need an 11 or 12 wt. for the tough conditions your encountering.