I am new to this board but have had experience with this so thought I would post. We have flown with both boys 3 times, First time my youngest was only 1, we chose to buy his seat, it was half price, and took both his carseat and his 3 year old brothers installed both on the plane, 2nd time boys were 3 and 5 again took both carseats and installed both on the plane. I should say my husband hates this, and I will admit it is a hassle, so last time boys were 4 and 6 both were of the weight that they could use a booster, so I did not take carseats, and requested 2 boosters from the towncar company. The plane ride was more difficult, 4 year old had more freedom and wanted to move around more etc, town car company had brought a van instaed of a town car and had two different boosters, one was not appropriate for the type of seats in the van. I complained but was told that is all they had. I called and complained and verified it would be a towncar that picked us up, it was however they forgot one of the boosters, only had one. I so wished I had just brough our carseats.
Lastly, in the van there was a carseat already installed that another child must have used earlier, it was one that I was about 90% sure had been recalled and it was not installed properly.
If you bring your own you install it so you know it is correct.
Just my opinion but to make a long story short I would take yours especially if your child is younger, it is great for the plane.