I ported from Broadvoice around this time last year. No problems. VOIPo support was great and the port took about 3 weeks. I don't know which entity "owned" my number at the time, but VOIPo support was able to give me an idea of whether there might be any difficulty just by providing them the area code & exchange.

Note that if you're planning to cancel your Broadvoice account, and if you've had it less than a year, you will need to return their equipment within some time period to avoid getting charged for it (I forget the details - check their website). I had been with them for 4 years and, despite several inquiries from me, they never requested the ATA be returned. Also, probably goes without saying, but don't cancel your Broadvoice account until the port is complete and you've tested the number with VOIPo.