I just purchased a Fishman Aura Spectrum DI for use with my Cordoba Flamenco guitars (Cordoba GK Pro and Pro Negra and 55FCE) and am blown away but the improvement when using the Fishman Loudbox Mini Charge amp (and presumably all Loudbox amps). These amps had a particularly harsh sound for the piezo pickups in the Cordbobas without the Aura, and the Aura improves things enormously with practically any of the selections in the Nylon bank, but particularly the Cypress/Spruce bottom/top models. I'm almost convinced it can't get any better.)
(An improvement, but not so much, in other amps)
These guitars use the Fishman Pro Blend preamp/pickups (set all the way to piezo, no internal mic), so I imagine the body is not included in the electronics, since there is such a difference. In any case, I am now a BIG believer in the Aura, but would like to get IR's particularly for my models.
The best solution I have found for Helix, Hx Effects is to treat the units as effects in the insert loop of the Aura - I have yet to try this with a DAW, since I am temporarily out of Helix, but the approach worked great with the Hx Effects (and GT-1, and OD-1x, and... and... and...)
Guitar -> Aura -> Send -> Helix (guitar in) -> L/Out -> Aura Return -> Aura Out -> FRFR amp (or Fishman Loudbox)
Of course, once you have applied the Aura, you can take the output of the Helix directly to an amp, but the Aura gives you important local control of the Aura master if you want that...).
Of course, the output of the Aura (without the loop) can be fed directly to the inputs of the Helix or HxFx….)
The Hauser IR from Sigma3 (for a classic guitar) may work with tweaking, but the Hauser does not have a pickup, so I doubt it will be as effective for the Piezo modeling.
I can't believe the sound I'm getting now after so many years of desperate struggle....