It depends on the army. Nids do it well at low levels but not at high levels. The "fexstar" (1 fex, 1 prime, regeneration on both, you get cover saves because half of the squad is infantry) is solid at 1500, but as points get higher your opponent's firepower magnifies and they can kill it quickly enough for regen to not matter. Other armies need to wait.
Units like TH/SS termis in raiders, bike squads in pure bikes, etc. really need to be taken in pairs. At lower levels you can't do that and support them, so it's out.
I'd avoid Lysander in general (even if you're playing Fists, just make an army that fights like Fists would), but overal building an unbalanced "top this or die" unit is bad news. You'll stomp some armies with no satisfaction for either of you while other armies just crush your rock or tie it up and go after everything else.
Her(?) name may be slightly inapropriate, but she just needs love! And I just need to eat your face!
I'm probably going to follow my usual Eldar tactic of driving around the table "circling and screaming 'I don't give a fuck' with my windows down and system up" and avoiding anything that looks scary.