I really like it and don't think it sounds overly pretenious. It reminds me of two things,
The Importance of Being Ernest, which is awesome, and
Flowers for Algernon, which is a book I love but always makes me sad. I think it's a great name but would never use it personally.
Out of your combos, I like:
Algernon David Algernon Francis Algernon HughAlgernon Hugo Algernon LeoAlgernon Louis Algernon Lucas Algernon Matteo Algernon Michael Algernon Samuel Algernon Silas Algernon Thomas Algernon Victor Algernon Vincent (
Vincent Algernon would be awesome, though)
Algernon William