HIB has a 15 second cooldown also, so you only need one dot per 15 seconds to be able to use it. Stockstrike has a 9 second cooldown, so it'll always be available sooner than HIB and the Ion Cell dot lasts 9 total seconds with talents.
Let's run some numbers with no mitigation.
Gut+HIB does 4500 damage in 15 seconds and costs 4 ammo.
1500+3000=4500
Stockstrike+Ion Cell+HIB+ Energy blast does 6700 damage in 9 seconds and costs 3 ammo.
2200+800+3000+700=6700
I rounded numbers a little bit and ignored resists because I want some quick and dirty numbers, but I think you get the point. Gut quickly falls behind damage and ammo cost wise, and falling behind ammo cost wise only makes the damage gap wider in favor of Energy Blast.
Edit: Yeah, I could add SS+Ion cell to the Gut totals, but then it would cost 6 Ammo and only win by 800 damage and the gut dot wouldn't be necessary to proc HIB... The ammo is where Energy Blast really works out. Even then, given that you have to wait 15 seconds to get all the damage out of the gut rotation means that it has a lower overall DPS and about half of the efficiency.
Edit 2: I know gut doesn't have a cooldown, but if you don't let the dot tick out then you are wasting half of the damage.