My transition to Vim has been pretty good so far. There are still a couple painful points though. One of those is with the fantastic CtrlP plugin It took me a bit of digging to figure out how to add my gems to CtrlP:

# Open Vim in working directory
vim

# CtrlP your gem directory
:CtrlP ~/.rbenv/versions/2.1.3/lib

# CtrlP your working directory
<c-p>

I also created a mapping for mine:

" open gem dir in ctrlp
nnoremap <leader>gem :CtrlP ~/.rbenv/versions/2.1.3/lib/ruby/gems/2.1.0/gems/

Then you can do something like: vim <leader>gem<cr> minitest<tab, complete for version needed><enter>

EDIT:

You may want to bump your max files in CtrlP with the following:

" unset cap of 10,000 files so we find everything
" src: https://github.com/kien/ctrlp.vim/issues/325
let g:ctrlp_max_files = 0