That depends... exactly how much recharge you have is not nearly as important as what attack chain you are running. If adding Spiritual lets you switch from Blaze -> Flares -> Fire Blast -> Flares to Blaze -> Fire Blast -> Flares, for example, then go Spiritual. But if it just means running the same attack chain with a slight boost to how quick Fireball recharges you'll be better off with Musculature.
However, since you are /Energy it's also worth keeping in mind that Spiritual boosts stuns too... you have a lot of them if you use the melee attacks and they probably aren't slotted for stun.
Cascade, level 50 Blaster (NRG/NRG since before it was cool)
Mechmeister, level 50 Bots / Traps MM
FAR too many non-50 alts to name
[u]Arcs[u]
The Scavenger Hunt: 187076
The Instant Lair Delivery Service: 206636
I play more at range, but if something gets close, I'm happy to punch it in the face, and you're right - I have no plans to slot the punches for stun. The info about attack chains is exactly what I needed - I hadn't even taken it into consideration. I'll look over my build and see how it stacks up.
Thanks.
@Roderick
As far as attack chains go, for ranged single target you are probably going to use Flares - Fire Blast - Flares - Blaze for a moderate recharge build. At a certain point Flares - Fire Blast - Blaze becomes better even if it has a gap in it... you need to get the gap down to around 0.3 seconds for the shorter chain to do more damage, which means a total recharge of about +200% on Blaze (enhancements plus global bonuses). At +229% the chain becomes gapless and no further recharge will help. The tier 4 Spiritual Core Alpha adds about 33% recharge to an ED capped power (I'm assuming you'll have Blaze ED capped for recharge) so if your total recharge on Blaze is between +167% and +228% without Alpha bonuses you'll get a ST damage boost from Spiritual. Below +167% you'll still have too big a gap to match the longer chain's damage and above +228% you're already gapless (and the amount of damage improvement declines as you move from +197% to +228% since any boost beyond +228% is wasted). As far as AoE goes, the more recharge the better since you aren't likely to have a gapless AoE chain.
If you go the Musculature route, you'll actually get enough damage boost at tier 4 to make Flares - Fire Blast - Flares - Blaze hit harder than Flares - Fire Blast - Blaze, but you won't get the added benefit of more recharge for your other powers. For AoE I'm not really sure which adds more damage over all... I suspect it depends on your recharge total since the more recharge you have the less difference adding more makes. If you have 50% or less recharge slotted in your AoEs (quite possible if using Positron's Blast) you'll probably get more out of Spiritual since you'll get almost the full 45%. At the ED cap you'll probably get more out of Musculature unless you have very low global recharge (and maybe even then, it's a little more complex to work out and I'm too tired to do so right now 
). More recharge also means using Build Up and Aim more often, but that probably won't make a big difference unless they're not near the ED cap or you have very low global recharge.
Overall I'd go Musculature since you aren't a Blapper (so the stun enhancement will make less difference) and you don't have any really long recharge powers on a Fire/Energy. Plus you use less endurance hitting harder than you do hitting more often. The only exception would be if Spiritual made Build Up and Aim available every fight when they were previously every other fight.
Cascade, level 50 Blaster (NRG/NRG since before it was cool)
Mechmeister, level 50 Bots / Traps MM
FAR too many non-50 alts to name
[u]Arcs[u]
The Scavenger Hunt: 187076
The Instant Lair Delivery Service: 206636
I'm working on a build for a Fire/Energy blaster. By the time I'm finished (before adding an Alpha slot), all of the attacks will be at or very close to 100% damage enhancement, and Hasten will be as close to perma as possible, probably about 10-20 seconds short at most.
At this point, in general, is adding a Musculature or Spiritual Alpha going to improve DPS more?
@Roderick