This was compared with same cartridge (Benz LP-S) on a WTT Signature (rare beast!) to a Funk tt with FX arm. Both are in no way slouches in regard to transparency and quickness etc.
Regarding the thinness of the Delos on the VPI: When I tweaked & optimized a Benz for a customer I was astonished at how audible changes above 0.01-0.02 gram were. Too low and one gets an exciting, but edge of the seat sound, that sounds stressed sort of. Too high and the sound gets a bit dull and slow in the bass, with a lack of open timbres.
The easy way to tweak is to set the VTF low and start with small, measured Blue-Tak balls, that are lightly stuck to the headshell. (Yes they change the sound slight by themselves - but more slightly than the weight change)
Too low or high VTF has obviously the opposite signature to VTA changes. I think that the changes with tracking force are only partially explainable with implicite VTA changes. And I feel that the effect is more pronounced than VTA changes.
If one starts to think about tweaking VTA and loading, my experience is that is crucial to really first tweak tracking force (VTF) by ear, with a precise digital tracking gauge. - And high precision & repeatability in setting the needle down on the gauge.