Obviously, there's problems with some units. Typically, this is for units like Nobz and the Death Company that don't natively come with much in the way of wargear, but can pile every squad member with Thunder Hammers and Power Klawz and whatever. I think anyone wanting to use Power Levels should probably put a sub-system in place to account for these, maybe doubling the unit's PV after it teachers a certain threshold of points value. These units aren't extremely common, so it's easy enough to work around them, I think.
They already "pay" for those options with massively inflated base power level costs. Trust me.
Death Company cost 9 PL per 5 dudes, 10 if you give them packs.
It's more like those units need the base PL dropped unless you buy excessive upgrades.