I ran 50/50 atf/cheap oil. Supposedly that's what Dowd preferred, even in his factory bikes.
My RM has this grabby clutch issue that as soon as the oil breaks down after the first day of riding, its a pain to take off smoothly. I was too cheap at the time to redo the entire clutch setup, so I played around with different brands and ratio variations, I ended up with 50/50 ATF with straight 30W oil. It worked good, cost almost nothing (compared to brand name gear oils), and you could change it as often as you would clean your air filter. I did try the redline shockproof... looks like a shamrock shake
It was really smooth and instantly noticeable in engagement, but still didn't last past the first ride for my problem. I also couldn't get over the thickness of it, it bothered me thinking that it would never fully drain out and I would be over filling it each time.
Long story short, yes, I tried the ATF and liked it. If you're a full-time 2-stroker, it will pay off in the end. No, I never fixed the clutch.... bought a new 450 instead