Not sure why you bought Sigma if you are at such odds with one of its core functions. The "respawn" occurs in select areas for specific reasons and is far from cheap. Learn to play the game or get to understand why certain things happen in it.
While I wouldn't go that far, I do have my reservations with both. The presentation, polish and scope are all certain to be there in spades, but I'm not sold on the gameplay or inherent fun of either - as in excecution, not concept (Lair more so than HS). If I can get this demo (haven't been able to DL anything in months due to connection issues) and it's a good reflection of the game that'll help greatly.
I'll refrain from any more comments on games not titled HS to keep from steering things of track. This is great news and hopefully a sign of more demo content coming with greater frequency.