One of the nice things about Rip is that it supports RubyGems so, to an extent, you can have your cake and eat it too. The collective investment Ruby developers have in Rubygems is pretty large, so if it gets replaced by something else, it's not going to happen overnight.
Definitely. I see Rip as a superset, of sorts, of Gems. That is, Rip is great for managing both Gems and in-development code, and doing so in swappable environments. Gems, on the other hand, tend to represent mostly mature code.
