C.S.
I had a Sit-N-Stroll and virtually never traveled with it on a plane. I bought mine 2nd hand on e-Bay and although it was used in the car for awhile, it was not my favorite car seat. It did not recline but had adjustable straps. It was awkward at first to change into a stroller, but I adapted eventually and they say it can be done with just one hand while you hold the baby in the other hand. As a stroller, I found the extending tubular handles a bit flimsey, and the wheels a bit small for taking on curbs or steps. The nice thing was that if you travel, you do not need to take both a stroller and car seat, but I don't think I would consider paying full price for one.
I believe I would compare it to the one mentioned in your last answer.
Good Luck!
C. S.