I've tried most of the combos out there and (for the 60/40 split you mentioned) I've settled on the Mefo SE rear and a Dunlop 606 front as the best combo for me. Not as Grippy as the Scorpions on the street but I can still grind toes in a corner and there's no replacement for a good knobby up front if you're serious about dirt. The TKC front works well but the weak sidewall caused a few rim dings with the stock wheels. The TKC and Rally Raid rears are excellent but wear out way too fast. The Mefo wears like iron but you do lose a little grip in the dirt; a trade off I can live with.
Just another Dharma Bum, drifting in the void