Hrm. I'm of the mind that Frenzy shouldn't be a discount. I'm not saying it should be costly at all (maybe free, maybe 1-2), but certainly not a discount they can use to game the system and render other units (i.e. Jeanne, Myrms) cheaper. Reasons being:
1) You retain the ability to grab Cover until you cause a wound. For some models, this can be very quick; for others, they'll only be doing damage once they're far up the table.
2) Once you cause that wound and can no longer benefit from Cover, you now have an extra order to exploit this position.
3) Often, though not always, units with Frenzy have some other sort of defence mechanism i.e. extra wounds/higher ARM, ODD, etc.
I often play against units like the aforementioned. It seems to me that, over long chunks of time, Frenzy rarely triggers when it is inconvenient. Mostly, it is either a neutral condition (extra order yay, no cover boo - and you can use an order to restrain the unit), or a positive (extra order gets you into position, allows you to approach objectives, etc.). I often find myself feeling like Frenzied units are a tad underpriced, and a correction to Frenzy might help with that.
That, or they stop applying Frenzy to units like Jeanne to make them even cheaper.