Define “solid” because in my fast and furious days of the 90s I had several real solid mounts and ain’t no way anybody is putting on or making those for anything but hardcore enthusiasts. I’m going to assume by solid you mean rubber/urethane inserts vs fluid. Mounts with rubber inserts can been good or bad with longevity depending on quality. Hydraulic mounts LOVE to fail, even oem mounts ESPECIALLY luxury cars like Mercedes and BMW. You could keep a business open just replacing Mercedes hydraulic motor mounts. Unless the mounts are “real” solid mounts (all metal) or made for performance (hardened inserts) NHV shouldn’t be an issue. Millions of car have factory rubber mounts without NHV.