Well, for one thing, its a whole lot easier to be otr in a straight truck than it is in a semi with a 53' trailer. For the driving part of it, after driving a t/t, driving a s/t is like driving around in a sports car - although I think I appreciate the s/t most when I want to eat or park it for the night. Generally you can pull into a nice restaurant instead of being confined to truck stop food, and so far I have never encountered a truck stop that I could not weasel my way into for the night no matter how packed it was.
As far as your income is concerned, I would say that you can expect to net anywhere between $300 and $1500+ per week depending on which company you haul for while driving someone elses s/t. My guess is that overall, the average net pay for s/t drivers who do not own the truck is in the $400 to $500 per week neighborhood rolling some 1500 miles per week - just a guess mind you based on my own experience in expediting and talking with maybe a few dozen other drivers who drive someone elses s/t - your milage will vary.
Overall, I have found the people in expediting to be much nicer, more friendly and professional than in "truck load", even the shippers. I have found driver respect to be much higher in expediting than in truck load - not that drivers are treated like royalty, but we are treated better IMO.
As far as life on the road goes, expediting is alot like otr in many ways. IMO, the main difference is that the delivery times are generally a whole lot shorter than in truck load. Its very rare to get dispatched on an expedite load going 400 miles that delivers in two days - more like 10 or 12 hours is the norm.
IMO, the worst part of expediting is getting that call (or QCOM) for an all night run, right before you are ready to turn in for the night after numerous failed attempts to sleep while you were sitting all day. That can be pretty rough.
All in all, I rate expediting a 9.9 out of 10 in comparison to otr in a semi. In comparison, its easy money, the wait times at the docks are rarely over 15 minutes and most of the folks you deal with are happy to see you......as long as you are not late.
My advice is do what I did and go for it, see how you like it. The only regret I have is that I didn't get into expediting a whole lot sooner!
Good luck!
Steve