chassis grounding is something I have neglected as a Hamm after it doesn't seem to help much at VHF plus ndeed most of my VHF gear can't be grounded very well
HF seems to be another story I found this out when I decided to ground my gear at the insistance of the intructions for the AL-811 amp.
I was shocked at the result. and then tried it on my older FT 847 which I had all but given up for dead at HF and the resulting improvement in prefrom was shocking
accordingly I have to suggest that no matter what your experences have been at VHFplus with gound try it on mf and hf spectrum