I just updated a TRADFRI open/close remote to firmware 24.4.6 (losing the group bindings) and bound 2 window covering devices to it via IEEE bind. It works without problems. So I guess the 5 button switch supports multiple bindings, too.
As deCONZ does not create groups/group bindings for Ikea switches anymore and you have to do bindings manually via deCONZ bind dropbox there is no drawback updating to the latest firmware anymore.