Hmm, I have the same experience as @dmx21. I installed also 4 FYRTURs 6 weeks ago. Since my pi4 is 2 floors up, I installed the Ikea repeaters distributed across my house (1 on each floor in the hallway). I only have an Ikea lamp next to the shades. I added 2 of the open-close remotes. I use ZHA with a CC2531 plugged into the pi4. So I guess you could say that this is indeed not a very big Zigbee mesh. But I have absolutely no issue with battery drain and it all works very fast. There has never been a no-response.
I have to say I paired the remotes to ZHA only and use an automation in HA to trigger the shades when a button is pressed. I did not bother with groups. So I just have an automation that lowers/raises 4 blinds on a button press trigger.
When I paired the remotes, I actually paired them in ZHA via the repeater devices. You can clearly see in my visualization that the buttons connect via the ikea repeaters. They have been doing that for over 6 weeks now with my batteries showing 87% in HA. I don’t know if the buttons stay connected to the repeaters all the time. I haven’t checked if they indeed sometimes connect via another powered device. But at least I can confirm that in my case the remotes connect to the repeaters and I have no battery drain issue (with ZHA).
EDIT: interestingly one of the remotes reports offline vey often (as you can see in the screenshot), but when I press it, it actually reports instantly in HA. So I never bothered looking into that.