Does the fact that it neglects to base it itself on Test::Builder mean that it does not play nicely with the stadard testing phase of CPAN style module distributions?

Yes and no.

T::U can be made to output TAP (using Test::Unit::HarnessUnit) which means Test::Harness can understand it's output, so you can integrate it into the normal CPAN testing phase.

This disadvantages are that:

• It doesn't support all of TAP - so you cannot use things like SKIP and TODO tests if you want to
• Since it is not based on Test::Builder it doesn't integrate with all of the other Test::Builder based modules on CPAN - so you may end up reinventing some existing wheels
• Since it's not a core module (unlike Test::More) you have an extra dependency to install.

Well - that and the fact that its huge, overcomplicated and pretty much unmaintained :-)

If Test::Unit seemed reasonably close to what I wanted, what is the closest thing that behaves in an appropriately Perlish fashion?

Test::Class - but I would say that :-)