Why on whatever planet of your choosing are you trying to enter a building in a 'Mech anyway? That's just plain asking for the environment to kill you before the enemy does.
If you've never seen a Trebuchet fall and slide into a light building, only to come walking back out covered in assorted womens' undergarments, I just don't think you're playing the game right.
(This actually happened in a game)
But yeah, I agree, if you're walking a Mech through a building, you'd better have a really good emergency-level reason to be doing it, because otherwise you're taking a beating for no reason. They cave in, there are basements sometimes... it's best to go around, or level it first and walk over the ruins. If you have hardened armor, all the more reason to be cautious rather than stupid.
That said, I wouldn't want to use this in a city either, but we don't always get to pick our battlefields- cities tend to attract attention in warfare, and your Stalker II might have to forget all its' troubles, forget all its' cares, and go down-town. If that ends up being the case, keep it on major streets- that will give it the ability to lob LRMs down-range at least. The eight lasers allow it to act as a Hunchback-style area denial weapon- park it somewhere good, and the enemy can't go into that area without taking a kick in the teeth from those lasers. And since this thing isn't exactly fleet of foot, keep it defended against flanking attacks, particularly from infantry- some battle armor make for a great defense, and a decent tank like a Zhukov or Ontos is a good way to make an enemy stay further back as well- even if your enemy gets a decent attack off, it's looking at taking a beating in return from the Stalker AND a nasty bit of armor to join in.
...Now that I write that, I just realized... Slow, tough, eight medium lasers backed by some LRMs... and built by the ex-FWL.
Stalker II = walking Ontos. Mind is blown.