Knuckle, I wouldn't call the YT performance comparable across the Roku platform. My 2 XS is unusable due to button press lag, as well as occasional crashing the Roku itself. My TV is usable, but it also suffers badly from button lag if pausing or fast forwarding. My Stick is even better, with some lagging. However, my Ultra and 4 work flawlessly in all aspects. My feeling is YT has designed their app for the most powerful boxes, and the lesser powered boxes are stuck with the lagging issues. Since I've never used an Express, I can't say how it might work in comparison. Looking at the hardware specs, the Express looks to be about the same as my Stick. https://en.wikipedia.org/wiki/Roku
Nvidia Shield, Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.