I began writing my Shrike vs Vulkan bit, and begin rating on the command squad, so I decided to bench the Shrike v Vulkan till next time... Here is where I went:
"Now for Shrike, or should I say Captain Shrike. Using the captain, your granted the ability to use the space marine Command Squad (which is given fleet!), Using this squad in a razorback is my favorite unit in the codex. As I run it, I have:
A razorback with twin linked heavy bolter
A Company Champion with 4 power weapon attacks on the charge with WS 5
A Veteran with 3 lightning claw attacks on the charge (re-roll wounds)
A Veteran with a melta gun to shoot that transport (out of the razorback if I can)
A Veteran with 4 attacks on the charge (chain sword)
And an Apothecary, who grants the unit feel no pain! I get a 3+ save, which if I fail, then get a 4+ re-roll save. This unit is so diverse, and it kills most anything it touches - all for the low price of below 200 points. This unit shreds any other marine squad it comes near (and therefore, just about anything else).
Now placing them in the razorback gives them a degree of protection from incoming fire, and allows them to get 12" out, then assault out next turn with (with fleet from shrike) a possible 18". This works well with my force well, as my opponent is typically concentrating on the dreadnought in the drop pod, and the infiltrating assault terminators with shrike, and 2x assault marine squads with fleet (possible 24" threat range) rushing up the flanks.
Now why not buy just another terminator squad for 200 points? Well, for that very reason I explained just above. This unit is so versatile, its perfect for any occasion. My favorite use? Pop that enemy transport from within the razorback with the melta gun then assault the troops within the next turn... Thats before shooting it with the heavy bolter. Also, your opponent wont call it cheese like they will assault termies!