I'm running 100mm Magura Asgards on my '94 Explosif singlespeed and, I have to say, I really like the setup.
I run the Asgards at about 25% sag and by tuning the oil levels/air pressures in the two chambers they use all their travel on occasion but don't blow through the midrange too easily. Even without any lockout facility climbing is good too, without much bobbing.
My favourite bike at the minute anyway - I took my 2007 RM Blizzard out for a couple of hours yesterday evening and I'm sure that I would have enjoyed the ride more on one of my singlespeeds....even with a few stiff climbs
The only unfortunate thing is that with this frame there is no "magic ratio" to let me run it without a tensioner - or not for a ratio that is usable anyway. Currently running 32:18 but may try 32:20 - I don't ride more than a mile or two on the road anyway so I could live with the spinniness in exchange for slightly lower gearing for the short steep climbs out of gullies etc.