Which artifact that here didn't pick do you think shall have a priority over Cache Boost then?
Either Quad Strike or Inspire Mercs.
I'm onboard with SAC, AcampB (for SAC+FC), TS, HB, AcacheB, AV, TW.
Cache Boost just isn't a big enough benefit to choose over QS or IM. Or even Money Cache Boost or Resource Cache Boost as these are material on the new levels. Not so much Huruey through HEH, but certainly Regio through Hex.
And with SAC, TS, QS, IM, it's likely that 3 and sometimes all 4 artifacts will be on cooldown at any given time. Certainly minimally 2. As long as you're planning well, there should always be either a large merc camp to drain using IM or a big territory to take down via TS, QS. So probably only have 1, max 2 artifact slots open. 1 should be HB, 1 should be the native Cache Boost any of Army/Money/Cache. I suppose Cache Boost could serve as a compromise for money & resource caches in lieu of having the native ones, but I still think it's too small a benefit to bother with. The only real use case for CB for army caches is with HB + AcacheB + CB, but then this implies non-optimal use of TS, QS, IM, and thus still not the best tactic.
Perhaps if sufficient IM powers (not artifact) are available, can forego the IM arti, but would still say QS is a better option.