I'm in the same boat as you, but I don't tend to voice my opinions on Test::Unit because there is such a strong opinion for RSpec and Cucumber. IMHO, I tend to like my tools to be tried and true, and not do any fancy magic.
There's a group of devs that have fooled themselves into thinking anyone outside their group understands how they are testing. I've seen this firsthand. DHH has always been right, imo, in this regard; test what you think is important, use simple tools.
TestUnit still serves me well and it perfectly fits my needs of do more with less.
That being said, to a developer writing tests and doing TDD, Cucumber is a speed bump that doesn't need to be there. RSpec is great without lumping more crap on top of it.