whole post if flawed by a misconception, just skip ahead, nothing to see here ...
Quote:
Originally Posted by bareel
Your premise is that full aux with STF shield will grant more tank than full shield power would when using TSS. Let us examine that statement and see if it is infact true (as I type this I do not know).
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It is flawed.

Flawed is your math, and flawed are your prequisites.
You forgot to include the 7.75% reduction from 50 shield power.
You forgot to include EPtS, which has the heal component, the shield power bonus AND the shield damage reduction all scale with AUX. EPtS is actually the makeorbreak for this scenario.
Assumption is always max power to weapons. No more than 25 power to distribute either way.
Assumption is also a raised power level to all systems from either M.A.C.O. shields or Plasmonic Leech, and of course Warp Core X and X Efficiency captain skills.
Assumption should also be that the incoming damage is plasma type, for another 20% reduction, at least in STFs.
Not that you'd be totally wrong, with only TSS and shield power at extremely low, AUX can't make enough of a difference (it'd still be a bit closer)  but that's not even remotely a realistic setting.
In practice, it's a decision between ~80 Shields (25 base > 50'ish from skills, +10(+) M.A.C.O./PL, +20'ish EPtS) and ~80 AUX (50 base > 70'ish from skills, +10(+) M.A.C.O./PL) versus ~95 Shields (50 base > 70'ish from skills, +10(+) M.A.C.O./PL, +15'ish EPtS) and ~60 AUX (25 base > 50'ish from skills, +10(+) M.A.C.O./PL).
Plus ship type boni, of course ...
I'd have to look up more precise values ingame, but the general dimension should be correct for now.
Double EPtS and TSS, of course, so that'd be a ship like Any Carrier (not that there's any discussion about AUX > Shields here, AUX boosts all Sci powers and reduces hangar bay recharge time, so it'd win anyway), Any Sci Ship (same as above, AUX wins by default), Cruisers like the Ody, Bort or Galor that can run double TSS setups (and profit from higher AUX for their hull heals and Eng abilities, though that one's a bit closer than Sci), or simply an Advanced Escort or tankBoP ('haven't really done the math for those yet, so if you revise yours I'm just as curious about the results, I'd guess it should be pretty close).
Results will differ depending on the total boost to system powers  at low levels, Shields will always win; inflate power levels enough though, and AUX draws ahead, it's not a static equation.
For a ohcrap tanking situations in PvE, there is no choice anyway  you max out both. PvP has healers (which max out both anyway, and need AUX to do their job) ... and for bursttanking situations against an alpha strike in PvP, Shield will always win, since that's all about effective HP, and AUX trades effective HP for sustain.
Personally, I'd be too lazy to do the whole math on this  if done right, you end up with a tensor equation. I'll still proveread any of yours, if you're less lazy. And maybe I'll supply a data point or two later today.