Honestly, I'd take Bio on the Guardian tank and swap the others to Cybertech (VG) and Artifice (Shadow).
Guardian tanks benefit from being able to swap between Might and Fortitude stims mid fight. I open with a Might stim on and then swap to Fortitude later when threat is less of an issue whereas my PT and Assassin tanks both just use Fortitude stims the whole time.
The only skills that are worth using on raiding toons are:
- Cybertech to RE Ears, Armourings, Mods and for grenades (<3 my 2nd AoE mezz on my Scoundrel)
- Biochem for reusable adrenals/stims/medpacks and the RE implants
- Artifice to RE Hilts, Relics and Enhancements
- Armstech to RE Barrels
Of those, only the Ear, Implant, Relic and Hilt can't be taxied between toons using legacy gear. Low level grenades stun just as well as high level ones and Exotech stims/adrenals are better than reusable Rakata ones.
EDIT: Of course, our raiding style is to RE for mats and schematics before giving to companions and to RE non-BiS mods anyway. If your guild is interested in gearing companions through raiding those things are a lot less useful, but if you can convince them to RE instead of gearing companions you can get a whole slew of Molecular Stabilisers.
Great advice, thanks.