I'm a Marik fan but even I think the Hamilcar is weird to the point of almost being useless. In every situation I'd rather use something else.
It doesn't have enough armor/firepower to be an assault ship in any meaningful right. Thrust is just ok.
The idea of a space assault vehicle is cool. But I don't think the designers really thought it through with the Hamilcar. It's too generic. It's just 'mech bays and aerospace fighter bays. You can send a Leopard or a Union on that mission and achieve much the same results in a spacecraft that can also serve in additional roles/tasks such as raids and planetary assaults better.
It's a Unitasker. Advertised as being designed only to do one thing, and it doesn't do it very well at all.
If I want a space assault vehicle, I'd want:
-A ship with the speed/armor/firepower to hold up in a fight, it needs to be a proper assault ship (or closer to one), it can perhaps get away with being a little lean on firepower since capture rather than kill is the goal, but it needs to be able to hold its own and defend itself reasonably well. Or perhaps a lot of speed, like the Achilles, with enough armor/firepower to survive.
-A combined-arms boarding team. Sure, let's bring 'mechs and some ASF cover, but we also need the small craft and conventional infantry marines or BA marines to actually take the target and secure it deck by deck. If you want to get extremely realistic, having some passenger space (to carry specialists or a prize crew to take control of the captured vessel) isn't a bad idea either.
-(This one is optional) I'd want the ship to have tug capability like the Model 96/97. If it leverages the other things well-enough, like the Nekehono'o with all its firepower and its veritable fleet of small craft and marines, I can overlook the lack of this. But this really is a helpful capability.
You can of course break down those functions across multiple dropships. Conventional marines on a separate dropship, a separate tug, prize crew on a separate dropship. But I just can't forgive the Hamilcar for being so inept at protecting its own 'mech cargo until it gets close enough to deploy them. And with its mediocre acceleration it can't control the engagement very well through speed/maneuverability.