If your career goal is to drive 777s then yeah, RJ time is better than Dash time. If you want to break into corporate, guess who is gonna be more qualified to fly a King Air?
I don't fly for Piedmont, but from everything I gather the "problem" with Piedmont is lack of a long-term future in newer/larger turboprops and the fact they're a wholly-owned subsidiary of US Airways. They have a very good CBA (better than most RJ operators in terms of work rules), excellent first year pay and you'll fly your ass off if you work there. Lack of a hub domicile outside of LGA for commuters could also play a role in recruitment troubles.
At least those were the considerations I had when sending out resumes...