So from this point on we also calculate the price of grenadiers as 240/60 just to make everything more complicated?
You would use that comparison if you wanted to compare volks with something like BAR'ed up riflemen, yes. And Panzergrenadiers dont have access to an AI upgrade.
It doesnt rly make sense to compare something that you barely ever see on the battlefield. Or when was the last time you saw an Obersoldaten squad without LMG34 being used against you, for instance?
The 3x Thompson package is a 0-downsides-upgrade for Cav Riflemen, there is no reason at all to not get it.