LOVE the chairs.
We gave DS his 3.5 years ago (he is 5 now) and he still uses it. The chair is about to be thrown away because the inserts are now sort of deformed and DS is getting tall but it was worth every penny. He loved it. We got DD one when she turned one. She is now 3 and her chair is still in great shape. She is not as rough with it so the inserts are not deformed like DS's. We still have the original covers.
Since your LO is older, I would consider the bigger chair so they don't outgrow it too fast.