I've just built a Sentinel deck for Type 1 and their big advantage (+8 attack) is just pointless to have. Nightmare just cancels it and Montana just laughs when they already get a -10 attack to begin with). Rescue... well... we won't even begin to talk about how overpowered they are.
Why even have a clan in the game that is totally neutered by everything else?
OK, Montana has a disadvantage, - 12 min 8 means you can't 0-pill without Hugo (a hefty 5 stars). Rescue has a disadvantage (can't use a leader, can't half-deck with suitable partners e.g. pussycats). The only one you haven't complained about, Uppers, is your only real opposition here...and I suspect they're MEANT to bust Junkz, in the rock-paper-scissors way the game has (the same way Rescue busts Montana without Hugo, as they do in the comics). I've got a few Sentinels, and I think that they're vastly powerful...I agree with Tfjoc that even without bonus they're mighty. Also, their bonus has no disadvantage. All you end up with is -2 att vs Uppers, in terms of direct disadvantages. If you can't surmount that, then...I don't know, maybe they are awful.