I flew at Lakes from late '00 to late '02. Granted it has been a while since I have worked there, but I can't imagine much has changed.
I was hired there as an intern and had very low time. I knew it was not a place to retire at, but I knew it would be great experience. Yes the pay, QOL, schedules, and most everything else sucked about working there. However, the crews (both flight and ground crews) were all awesome and there was no better experience than flying a turbo prop with no auto pilot or flight director in the midwest, especially in the winter and IMC. I can honestly say my hand flying skill after flying an RJ for the past 8 years are no where near what they were when I was flying at Lakes.
Regarding moving on to another major, back in the early 2000's we had plenty of guys go to UPS, FedEX, UA, and every other major out there. I'm not sure how BE1900 PIC time is viewed these days wth all the RJs, but I imagine it doesn't hurt.
If you have low time and your only other option is flight instructing, I'd open your mouth for a poop sandwich and go to Lakes for some good turbine time. If you can't hack it long enough to upgrade, you will have good experience to go to another regional.