I know you said open heel, so I'm just throwing this out there in case you haven't thought about it.
I went to Hawaii in April. I took my Atomic Blade fins (which are great!) and my Mako Competition Freediving fins.
Competition Freediver Fins | MAKO Spearguns
I used the Mako fins for shore dives (Ho'okena, which has a lot of rocks in the water as you're wading in), and boat dives. I never did use the Atomic fins.
The Mako fins work better for me than my Atomics or my Hollis F1 fins - and that is for every kind of kick including frog kicks, helicopter turns, and back kicks.
And the Mako fins turned out to be surprisingly travel friendly - as long you take the foot pockets off from the blade portion. The blades are very thin and flat and easily pack in the bottom of any bag or suitcase (that is long enough, of course). Once the blade are removed, the foot pockets are a lot smaller than any complete fin and also pack easily. And the total weight of the fins is still pretty light.
Originally, I was concerned about how easy/hard they would be to put on. But, then I saw instructions for donning on the Mako site. It says to turn the heel of the fins inside out first. Then slide your foot all the way in, then just grab the tab on the heel and pull it over your heel. That really did the trick for me. Even on a shore dive, I would just wade out, carrying my fins. Get into waist-chest deep water or so, and slip each fin on and pull the heel cup over. It was no problem, even on a shore entry with 2 to 3 foot waves coming in. I've also done the same thing on a boat out of West Palm Beach, FL. Carry them and walk up to the boat's egress point. Put them on at the egress point and then giant stride in. No muss, no fuss.
If I'm diving warm water and not planning any kind of wreck penetration, my freediving fins are my absolute favorites!