OK, it looks like the DTH which has been created does not check the timing on the hold, so it won’t work easily. What people are doing is using the long press as a scene indicator, typically something like so:
That’s not as good as the other dimmables (love the Lutron, obviously 
) but it may be better than just two buttons.
BTW, everything I’m seeing from the technical side says a max of 12 accessories on one hue bridge, not 10. For what it’s worth.