Wow, it's even worse than '
Haven' which is how I would say it. I can't imagine many would think to pronounce it as '
Heaven'. It just wouldn't make sense.
One of my naming pet peeves (and one that is mutual among the name community) are Y-replacing names. They look juvenile and make the parents look illiterate and dumb. Basterized spellings such as Landyn, Camdyn, Emmersyn/Emersyn,
Jordyn,
Camryn,
Londyn and so on.
I don't reccomend '
Haven' but at least the spelling isn't an eyesore.