Hi, so the Pros arrived yesterday and I have spent some time switching between the two for (personal) sound and fit comparisons.
With regard to fit, I feel that the pros not only feel more comfortable but they also feel more secure in the ear. The Gen3 don't feel like they would fall out and I have honestly tried to get them to by jumping about but they feel like a knock could cause them to. I don't really understand why the pros feel more comfortable as they look the same size, but I guess it's because they are held in more by the bud. Eating and jumping etc do not cause the pros to budge, at all.
Onto sound and I am really amazed how good the Gen3 sound compared to the Pros they are fantastic! I think I would actually give the Gen 3 ever so slightly higher marks for bass. All together though the Pros do sound better (really close though). I tested with Noise Control switched off so I think it's just that seal.
Returning Gen 3 today. If the Pro was not an option, I expect I would have waited longer to see if the Gen 3 settled in.