For what its worth, im not on their flex kit yet (MY 2021 not supported yet), but I've been extremely happy since switching to their IS38 tune and plan on going flex as soon as its available.
From my experience after having gone through multiple tuners, I honestly think from a drivability standpoint IE's is one of the best for a non custom tune. There has never been a moment where I felt like I was driving a tuned car, and what I mean by that is, While all the OTS tunes you can grab are great, I had little things with most of them that would bother me (The way boost would come on, how sensitive the throttle is, small little hiccups in certain conditions with part throttle/normal driving).
I dont think you'd be disappointed switching unless you had aspirations for big hybrid custom tuned setups.