Would substantial jet time (wide & narrow-body) have any effect on turbo-prop/jet allocation for DEC's? And is SOU a base open for DEC's?
No. There's currently no chance of getting a DEC on a jet. The 195 will be crewed mostly by 146 crews and there's a list as long as your arm of Dash 8 people that want to transfer. They need Dash Captains and it doesn't matter if you have 10,000 hours on jets and none on turboprops - to the Dash you will go! Any transfers to the 195 will be a long time coming and will go in strict order of seniority. Recently, ex BA and Cathay Pacific pilots have joined - all on the Dash. Don't know how long they'll stay mind!!!
As for SOU, yes if there are vacancies. They're fairly receptive to Captains holding out for a particular base. Not so for FO's, but a lot seem to get a move within a year.
Hope that helps.