Just an observation:
A squad of 3-5 PCs can form most common guard units, depending on preferences and numbers.
10-man infantry (veteran) squad (w/comrades)
6-man fire support squad (3 heavy gunners w/loader comrades)
Hellhound crew
Leman Russ crew
Storm Trooper squad
The one thing they can't do (in the basic rules) is a sentinal squadron. Which, if main battle tanks are in scope, doesn't seem unreasonable. Recon being a single squad with an attached sentinal is fair enough, but personally I would consider the Hunter-Killer unit, which talk about being light vehicle units, and who all have operate (surface) as a standard skill and no decent weapons or body armour, should get either one Hellhound per squad or one Sentinal each .
Does this seem reasonable, or am I missing something?