X mark pro - can be tuned up and made respectable but not great. Reliable in field conditions
Jewell - can be made "bench safe" down to 1.5-2.0oz, and field safe at 1lb+. Not terribly reliable in the field and must be kept clean... I've never been able to get these to provide a really clean, crisp break.
CG Extreme - Can be adjusted down to at least 1lb, and is field safe if adjusted correctly. Excellent and clean let off, but lacks an over travel limiter adjustment. Not sure how field reliable they are. Mine has survived rain, cold and some dirt...but I don't think I've thoroughly tested it.