Thanks for finding this and replying.

It's ok to leave mapping guidelines to the local groups that add OSM trails. I just wanted to ask if there has been any MTB related effort in unifying our OSM mapping approaches. As for using something that renders OSM data better for MTB use, someone would have to step up to the plate and run a tile server for that. For now I think HikeCycle is good enough.

Since I wrote the OP there has been a game changer: Strava released its global heatmap. There is even an OSM editor that uses that heatmap data and, just yesterday, I got AlpineQuest to support that heatmap as a map overlay. AlpineQuest is an Android outdoor mapping app. It's only a matter of time until someone gets that heatmap into a Garmin format.

The link for the slippy map is not working for me right now. I'll have to try it again later.