The more I think about it, the more I realize that the biggest problem with Assault Bots is that they are far too "spammy" to really be considered "assault" units.
Thugs: When I look at the primary assault units of each factory, I would choose almost any of them over the Thug. They are almost all higher cost, more powerful units that I can use more effectively. It takes so many of them to actually do damage, and by the time you get enough of them to lead a charge, it's hard to concentrate all that power on a single point because there are too many to get close.
Felon: I think the Felon is a bit of a specialty unit. It's either really awesome or really sucky. I think it's primary weakness is the "true cost" of the unit - you need two shields following it around for it to have any sort of sustained fire. Then those two shields require 14 energy each to recharge, which means you need an entire fusion to sustain the damage. This bring the
true cost of a single Felon into the 2500 metal range. Their assualt-then-skirmish gameplay mechanic also leaves them very vulnerable right after their burst damage and doesn't match the assault theme. They have almost no health and rely on their shield for protection. Once their shield has been depleted from firing, a few raiders can easily take them down.
The Racketeer, while useful at times, is also UP. Its base stats look OK, but it's much more micro intensive than other artillery units. Let's take a look at a "standard" artillery unit: something like a hammer, pillager, or even Merl. You point them at the enemy porc wall with a "fight" command. They shoot the nearest target until it dies, then they move on to the next target until it dies.
With the Racketeer, this method leaves you stuck with a dozen racketeers all firing on a single structure. In order to truly use them, you must manually set a target for each of them to spread out their fire (wow, that's a lot of micro). But then, that breaks the auto-skirmish that you need on an artillery unit. So it requires even MORE micro and attention to constantly look for enemy raiders, and if any are spotted heading towards your carefully-targeted Racketeer, you must then retreat the Racketeers, thereby also removing your clever targeting. So while their base stats may look good, the extra micro attention really removes a lot of their usefulness. (Perhaps a smarter auto-skirm for the Racketeers is needed? One that focuses firepower on a structure until it is stunned, and then leaves 1 Racketeer stunning that structure while the other racketeers move on to the next structure?) Also, I feel like the Merl/Racketeer are very similar, but maybe their roles should be switched? Light vehicle already has a more-or-less standard "damage" artillery - the Wolverine. Maybe give the stun arty to the Merl and make Racketeer a standard damage artillery unit.
Roach is probably a little OP for the cost, but that is fine at the moment because of the general UP-ness of shields in general.
Bandit is fine.
Rogue is a bit spammy for an "Assault" unit IMO. It's hard to get enough of them together to do concentrated damage. They end up spread out over a large area, unable to fire.
Vandal: One of the cheapest, spammiest AA units in the game (on par with Jethro). Suffers the same fate as the rest of the shield bots: they are too cheap and it makes it hard to cram so many in a tight space. The is not currently a mobile version of the Hacksaw - maybe something similar for assault bots? A strong AA unit that deal burst damage against air seems much more "assaulty" than a "pew pew lol I'm a vandal" unit.
Outlaw: Already explained their shortcomings. Can't stop crawling bombs. Can barely stop raiders unless hidden behind Thugs' shields to absorb the initial damage.
What I'm getting at is this: you win games by dealing damage, and the assault bots are unable to deal damage effectively. Thug has terrible damage, is easily countered by fire/emp, and because you have to spam so many of them, it's hard to get them all bunched up enough for them to concentrate their fire power. A single tick or roach wipes them out because Outlaw can't effectively stop them. Rogue needs a cost and damage boost, keeping the overall cost/damage ratio about the same but allowing fewer to be made for the same effect. Racketeer needs to be made more useful by making it easier to use (not necessarily buffed, just the necessary micro needs to be removed). The Felon might be OK if the other units get buffed, but at the moment is is the only shieldbot capable of stopping ticks and roaches and it costs too much metal to be used for that role. The vandal is another spam unit that barely does damage.
In the end, I see that cloakys should be comparable to light vehicles, and shields comparable to heavy tanks. Increase their health and damage output. Make them seem like beefy, powerful units that should carry the "assault" name, not another lab full of spam units. I think it will further differentiate the roles of cloaky vs assault and make it a more unique lab.