[Left of West]

That's a reasonable distinction.

I contend, however, that when you're buying multi-role units, you're paying for each extra bit of utility.

Sure, a Hammerhead is good against both, but it's not a cheap tank. You get better anti-tank for the points by taking Broadsides, but they're not really any good at anti-infantry.

So, yes. You can avoid the pitfalls of a cover-your-ass list (I like your terminology) by making a list with nothing but multi-role units, but that list comes with its own set of weaknesses. Namely, a multi-role unit is never going to be as good in any particular role as a dedicated unit.

Even your 'true all comers' list is going to be weak, to a degree, against an army using Kroxigor's principle. Though each of your units is going to be able to perform against whatever type of unit he loads up on, they're still going to have spent extra points on upgrades or options which aren't really doing them very much good. Their value to cost ratios are still going to be lower because you're not able to put all of those goodies you bought to use--and the Kroxigor list is still getting an advantage out of loading up on one type of unit while forsaking the others.