I'm curious as to how an alto flute scores over a C flute.

There are quite a few Scottish fiddle tunes that go down onto the G string - things like "King George IV". Currently one of my favourutes is Paul Cranford's The Graveyard of the Gulf, which ranges from the G below the staff up to the C above it - it was written for scordatura tuning. Scottish and Irish trad never needs the top end of a C flute's range, so an alto can do everything that turns up in practice, and it seems to fit better with voices.