The lack of a steep approach kit on the 135s would be a problem. The only one that was fitted with this had it taken out. I think it was ex airlinks operated from Ireland.
There was always a statement that they couldn't meet the performance even though luxair and the Irish one could. Don't think there is a credit for the reverser fitment on the 135.
They did wet lease a turboprop years ago to operate LCY from Leeds if memory serves but it was cut before it could develope. Seems to be a similar story more recently.
Was talk of new airframes prior to 2007 but still no sign. The 145s must be getting a bit leggy now.