Yeah, I'd like to see more parity in all leagues to at least minimize the use of handicap, but there will still be sandbaggers that try to exploit the system. The only scratch leagues I've seen around me are usually summer Sport/PBA leagues and those are usually singles that many lower average bowlers get into for the fun of it.
I like the idea that bdgf06 describes and I've heard of it before, but again it comes down to get enough bowlers that don't have an issue of bowling with someone they might not know. I wish there was one like that in my area, I'd give it a shot.
On the topic of percentage though even at 100% I still see the top teams more often than not be at the top of the standings, but I prefer something more around 90%. My current league is 80%. To me it should serve as a reason for one to improve to make the field level based on their skill not because they get so many pins added to their score. On both sides of the issue the bowlers need to know it is a handicap league, or tournament and that they are entering it as such. The higher average bowlers shouldn't complain when they lose based on handicap and the lower average bowlers shouldn't complain because they lost to someone with greater skill despite the handicap.