I got comfortable in an airplane and making decisions by being a CFI. I'm not sure I buy that the experience in the airplane is all that useful further down the line...that is to say, I can't think of anything S-Turns have done for me lately...and I did plenty. You also might consider what the goal is. I always wanted to fly cargo (it was just happenstance that they were the only people who would take me

) so CFIing was a must to build the time. If you are commited to being a people-pilot, maybe it makes sense to go zero to hero. I like everything about freight (ok, maybe not the hours) and I don't think I'd fit in well in the 121 pax world, but I get a little tired of hearing guys getting bagged on because they take a "short-cut" (not saying anyone here is doing that). I'd have taken a short-cut too, if it had been offered, and so would everybody else, presuming it fit within their ethical framework.
More concretely, the concerns others have raised are legitimate. One must always try to plan for the unexpected. Will you get furloughed? If so, what chances will you have elsewhere? If you go for the short course, will you have 135 mins should the unfortunate happen and you're looking to put food on the table? For my part, my strategy has always been to A) Make a reasonable wage and B) Always be moving up...need multi? Get it. Need turbine PIC? Get it. Make yourself marketable. I enjoy the heck out of my job and I feel like I'm treated reasonably well. OTOH, if my contract were up tomorrow and UPS or even say Kalitta called...I'm out the door.
I guess the point I'm trying to make is that you should always focus on what will be best for your long term goals. Be the pilot you want to be, not the one someone else thinks you should. I say this as one of the guys who would swear on a stack of bibles that you're not a REAL pilot unless you've done a circling NDB to minimums in a thunderstorm partial panel single pilot. But in the end, that's all just (mostly) bluster. If you do a sober analysis and it seems like a good idea, get your stuff in and start moving up.
Clear as mud? Totally unhelpful? My work here is finished!