Over the years I've converted a number of applications from DPB PowerBuilder 7.0.x to later versions using EA-Server with (virtually) no performance hit. Unfortunately EA-Server looks like it's at the end of its road, that and it is a bit fiddly (to say the least) when converting objects from DPB. If you want to go this route hopefully you have a good foundation in your DPB code so that you only have to make a few changes when you step into EA-Server.
The above said, I still have two clients running DPB applicaitons and they're in no hurry to upgrade. Oddly enough they are both holding out hope that SAP will dust off the old DPB code and put it into PowerBuilder 15. While I'm not holding my breath, I'd love to see that done as well. 