Emerald do seem to be putting a lot of effort into establishing themselves, arguably a little more than Flybe. Emerald have the benefit of the backing of the Aer Lingus brand and booking systems, a recognised brand in Ireland as well as the U.K. Between them and Loganair they do seem to be tying up the regional market.
For anyone confused about the Runway at SOU, even Flybe Mk1 had restrictions from time to time on the Dash especially when operating some of the longer flights, a tech stop on a hot day wasn't unheard of. Combine this with LM, SI, T3 and GR all operating aircraft that are restricted its obvious that the extension is more to benefit the regional market and to ensure those aircraft can depart full rather than to create an attractive airport for someone like Easy.
If Flybe do have the resources and will to set up a base at SOU hopefully it will be much more successful than T3, however if it was a case of putting eggs in baskets I think they should focus more on LM and Emerald.