First Watt J2 or F7 for my Omens

I have decided to pull the trigger on either a First Watt J2 or F7. Has anyone compared/heard these two amps with Zu Omen speakers? There is not a local dealer for these amps within 250 miles.. I understand the J2 has balanced inputs, 25 watts in 8 ohm and 13 into 4 ohm. The F7 does not have balanced inputs and is 20 watts at 8 ohms and 30 watts at 4 ohms. Any constructive comments appreciated!
I can't speak to your exact combinations, but I have something very close. I have the F7 paired with the Zu Soul Superflys and FET 10He. Sound-stage is huge, micro-detail is through the roof, bass response is excellent and good upper frequency extension. Amplifier fleshes out individual instruments and performers on the stage with ease. Quality live recordings sound like your in the 2nd row. Poor quality recordings really sound like crap. The F7 with the Zu's really shine, substantially better than the F5 or F6  I also own. The F7 is a fantastic amp for money! 
That is very reassuring. I like the fact that the 4 ohm rating goes up as apposed to down, compared to the J2;  should I ever try to mate it with a 4 ohm speaker. I also forgot to mention I plan on paring it with a Audio Research LS3.  This first Watt thing is apparently like buying your amp at Baskin Robbins. 😎
Your preamp might be a bigger factor than the pairing with the Omens. J2 has a much higher input impedance than F7, so if you are using a tube pre with high output impedance, J2 might be a better bet.

Edit, I see you are using AR LS3... their website says recommended load 60k ohms, so I'd lean toward J2.