Leo is my #1 fave male name of all time and I adore it for all of the reasons you've mentioned. I've had three dds and considered three possible male names and I've liked none of them as well as
Leo which is pretty funny since there never will be a little
Leo Gabriel. I still love it and hope someone else will get to use it if I can't! I worried about its popularity when
Penelope Cruz and
Javier Bardem used it for their ds, however, I'm not sure it will suddenly shoot to the top of the charts or even to the top 100. At least I hope not. I've never known any men or boys named
Leo or
Leonardo. I have known a few named
Leonard, however, they were all called
Len or
Lenny (yuk!).
Delphi is nice even though it's not my style. I used to know a woman named
Delfina and I thought that was beautiful. Overall, I'd prefer Delphi as a nn for
Delphine or
Delphina.