Padrino might be a good counter-example, because I think maybe it occupies a similar niche as merb fell into (I can't say for sure, because I've only used it ve

Padrino might be a good counter-example, because I think maybe it occupies a similar niche as merb fell into (I can't say for sure, because I've only used it very experimentally). But it took a long time from the merb-Rails merge to Padrino existing (at least 2 years, I believe).