After some thoughts about a round against Doom this evening I considered it would improve the gameplay for both hale and the mercs if this boss would get some changes, with the major problems of him being very dependent on luck with the pickups and having a very long sentry stun but no merc stun (also thanks to Jamie for helping me with the ideas).
The stats are showing that indeed people lose with him more than they win (1311 global hp mod. W:526 L:628) and it may be worth a try to change the things I mentioned above, giving him a "normal" stun against mercs and making the sentry stun shorter.

I would agree with you. Doom is really luck based to play and is no fun to see people hiding for power ups. And yes, the sentry stun is way too long. To be honest, it would be great if Doom could stun people so it would be kind of fair for everyone.