Mike E., I'd def. go ahead and plant your 3 gal. My three from the same crop have been in the ground for three years and they are doing OK. They've been through a couple of frosts with no protection but I usually cover them if it's getting below 40 F.
WARNING: The following is a shameless commercial plug:
I'll have some of these this coming weekend at the Palm Beach Palm & Cycad Society Spring sale at the Mounts Botanical Garden in West Palm Beach.
P. ekmanii in front and Cousin Hemi (Hemithrinax ekmaniana)is in the background. A happy family....
Great palm topic. This species is unlike any other, even the other 3 Pseudophoenix. It looks like a sculpture. I got mine from D'asign Source in Loxahatchee as a 1g in '08 or '09. I planted it right away. The tallest frond is maybe 30" now. No sign of a trunk. I protected it during the harsh winters of 2009/10/11 but left it alone this last winter. Nothing seems to faze it one way or another - it's a palm in its own orbit. Still, very cool and I'm glad I have it.
Pseudophoenix ekmanii
Side views
Tallest frond and new spear
I have this one in a 3 gal. It is ~13 years old, and has some cold damage from the bad winter a few years back. Got this from Mike Harris (Caribbean Palms). He probably has some left. It puts out about 1 leaf / year. One of these years it might be large enough to put in the ground.
Here's mine 2 years ago when I planted it. It's taken two years for it to grow 1 leaf. It seems to take SoCal winters like a champ so far. I only water it by a hose, every once in a while, only during summer. It's a tough plant, like a cactus, but it's sooooo slooooowwwwww.