Victory Smite fTP distribution, with possible DA (ignoring TA):
2.25 + 1.0 + 1.0 + 1.0 [+ 1.0] [+ 1.0]
With both gorget and belt, the first hit is increased to 2.45. With WSDmg from Shura+1 head, that becomes 2.5235.
Overall increase due to fTP and WSDmg compared to only using the gorget: 5.5235/5.35 = 3.24% to 7.5235/7.35 = 2.36%
Assuming capped fStr and Vere90 or Vere99, total base damage before WSC would be 98 - 106.
A hume WS set could have somewhere around 175 to 225 str, depending on gear, Boost-Str and Minuets, etc. That translates to about 90 - 115 WSC, and a working range for total base damage of 188 - 221.
+1 WSC in that range is worth 0.45% to 0.53%. To beat the value provided by Shura & Belt, you'd need 5 to 8 WSC, or around 10 to 16 str. With relatively low DA rates, you really need to be more towards the top end of that for an overall better average, though the requirement is lower if you have a lower starting str (eg: using Boost-dex instead of Boost-str).
Wanion+Aias matches the minimum requirements (net gain of 10 str). At the high end, Wanion+Nemetona gives you 15 str, or Wanion+Usukane gives you 11 str and 4% DA. And we aren't even bringing in the value of dex, though if you got that as part of your Shura+1 augment, it's less of a difference.
Also not seeing where you're hitting a 3500 average against anything where Madrigals (assuming that's part of the dex component) are necessary, or where accuracy on the belt can make any difference. I'm having a hard time getting the average much above 2700 against a level 110 target, never mind a level 120.
Of course then there's Conserve TP. It generally has a very small impact on overall DPS, though that fraction grows larger as your x-hit goes down (ie: it's worth more if you're TPing in Thaumas body than if you're TPing in Tantra body).
However, in pushing rounds per weaponskill down, I did finally get the contribution of the elemental belt (or more precisely, the Conserve TP of the elemental belt) up high enough that overall DPS was in favor of that over Wanion, though just barely. If accuracy mattered then it would clearly beat the Wanion Belt, but if accuracy really mattered then Anguinus would still beat the elemental belt. If you're not sure if accuracy matters, though, the elemental belt is a good option.
From my spreadsheet using Pil as a target, mdk's gear sets (~5.65 rounds per weaponskill), capped stats, and adding in weaponskill delay (was left out of mdk's calculations, and favors Wanion slightly), the weaponskill damage per second is:
226.25 @ ele belt
225.71 @ wanion
or 0.24% in favor of the elemental belt.
For anyone not pushing those limits, though (including all the necessary support buffs), it seems inappropriate to continue to present it as the best option for 'most' circumstances.