The whole concept of the Broadsword is cool. It's like a wish list of macho military space opera fantasy epics. Lots of guns? Check. Armored? Check. Room for some soldiers? Check. But when you get right down to it, it's pretty impractical. If soldiers are being transported from Planet A to Planet B, three parsecs away, and the ticket is let's say security or cadre, how important are the guns and armor? Not very important. You don't need to shoot your way into Planet B to train some backwater army or guard their starport. But you're still paying for the weapons, armor, and other eccentricities of that ship! Worse, it only carries about 30 soldiers. Tickets for a single platoon just don't pay enough to justify the mortgage of an 800-ton, MCr300 starship. It's just not practical.
Switching from a mercenary campaign to a merchant campaign, a free trader or subsidized merchant is hugely practical when it comes to transporting and trading small volumes of goods. Just about every aspect of that starship is a viable part of the investment every time you jump from Planet A to Planet B. It's basically a flying cargo hold and may or may not include weapons, depending on the lethality of the region.
I've run two mercenary campaigns over the years and both used the Broadsword. Why? Because it's cool and it's part of game lore. But both times it required major hand wavyness to justify this impractical ship being held in private ownership. It would make a great deal more sense for corporations to own these ships under certain circumstances: a) high pop region; b) lots of instability and conflict, and c) a lack of governmental cohesion in the area. Under these circumstances, it would make sense to lease Broadswords for short-term operations that require both troop transportation and a necessity to blast your way into and out of the combat zone. Perhaps a community of mercenary companies could use a single Broadsword and each would only lease the ship when performing a strike, commando, star marine or other ticket that required starship firepower. (I guess the players could only perform those kinds of tickets, but the campaign would probably get boring pretty quickly without more variety.)
While the Broadsword is full of questionable design choices, the one that always got me the most was giving staterooms to all the soldiers. Low berths would make a great deal more sense with their reduced life support and tonnage per soldier transported.