I like the list. It is similar to one I just recently fielded. The lack of a Wraithgate is troubling though. For 50 points it is certainly worth bringing, especially for the Shining Spears (my all time favorite formation). A centrally located Wraithgate can help you dominate the middle of the board when playing against an experienced player and is a deadly trap against the novice. Even against good players I've had games where Warhounds or Leman Russ crept a bit too close to the Webway Portal and were obliterated. Having this extremely useful formation offboard and away from BM dropping artillery or aircraft is essential to the blitz assaults. Priming a Leman Russ formation is a single BM, then CCing the units with Shining Spears means you are going into the assault with a +3 in your favor (assuming two Exarchs for you, one Commissar for him). He CCs at 6+, you CC at 4+. Your armor is effectively identical since you are armed with lance weaponry. You should come out slightly ahead on kills which means you could be looking at a +4 assault resolution.
I won't even tell you what I've done to players' Warhounds with those beasts.

Personally I think your list is AA heavy, which means you could stand to drop a Falcon troupe. Those 250 points would be good for:
50 pt Wraithgate, plus...
200 pt Guardian formation plus MW platforms (which could also use the gate), or...
200 pt War Walkers (my second favorite formation), or...
200 pt Jet Bikes (good ol' standby), or...
200 pts of Rangers (1 or 2 formations).
You would have the same number of activations or more, have a wider variety of units, and more options. The rest of the list looks great!