Well, forgive me if I'm out of line, but that makes it sound like you have endurance issues if you don't pace yourself. I tried out your build with the changes I posted about earlier (plus a few more) on Justin, and I was pretty pleased with the results. Just seems a shame to have so much melee and AoE defense and no powers to really take advantage of it.
But I did notice a few other things you could improve on your build. For example, why Positron's Blast in Fire Breath? You could put Ragnarok in there and get better versions of all its set bonuses. You could even 5-slot Ragnarok minus the Damage IO, and keep the Positron's proc in exchance for losing the toxic and psi resist bonus. Also, you've six-slotted Ring of Fire with Enfeebled Operation to get the melee defense bonuses, but since you said your playstyle is to hover out of range and blast, why do you need the melee defense? You could put an Apocalypse or Gravitational Anchor set in there for more global recharge, for example, or put the slots into Melt Armor for some recharge and accuracy, or put some slots into Fly and Afterburner to make them faster.
Lastly, about the endurance thing. I break into hives if I don't try to maximize recovery, so when I tried the build on Justin I changed the slotting for Cauterizing Aura. Instead of the Preventive Medicine set, I put 2 50+5 End Mod IOs, 2 50+5 Heal IOs, and a Performance shifter proc, and moved the last slot to Stamina for a 50+5 End Mod IO. (This cost a little global recharge, but I made some of it up by swapping the Positron's Blast in Fire Breath for Ragnarok, like I said above.) I actually forgot to slot the Panacea proc in Health, but had absolutely no end problems without it using that slotting, so you could put the Preventive Medicine proc in Health instead so you don't have to lose that proc.