The i3 KP has 4 buttons, with (by default) the top button controlling the load.
The i3 KPs unfortunately only have 4 buttons, and one of them (by default, the top button) controls the load, so you'd be sharing a "load control" function with a scene controller function on the same button. There's probably a hacky way to handle this with programs or other work, but I don't think it'll be nearly as clean as what you have on your 8-button KPLs.
The i3 KP can be configured to set a different button to control the load, but unfortunately it's only done so via Insteon Hub & Director app - eisy does not (yet?) support this feature. A few of us started another thread specifically related to that aspect, where Insteon confirmed they've provided documentation over to UDI on how to integrate this, so perhaps it's only a matter of time on that item: