JA, I think it would be better to keep things as simple as possible. The last thing we need is for each player to have 7 character sheets. So I think we should all just get "men at arms" with no other option. Of course, that could be women-at-arms for Catylina.
So, assuming that will be the case, what would our options be for the "men-at-arms"? I assume they would be 5 1st level warriors and 1 2nd level warrior.
If our options are Men-At-Arms, Heavy Crossbowmen, Light Horse and Heavy Horse, then what are each of those like? Equipment, capabilities (such as firing bows rapidly, if any of them can), etc.
If you don't take my suggestion to restrict us to the "men at arms", then you'll have to explain what you meant by "if you chose character classes then your use of them will be more limited" and by "roll them up as npcs".
BTW, a rules question: Does fast healing work below 0 hp? I've seen people think not, though that never made any sense to me. This makes a difference to how useful the spell infernal healing is.