i have found with my BA assault list (which i might add i have had such before the new codex) that the SG are good as support troop choices but not as a core. the artificer save can be negated too easily and they just don't cut it in a straight fight.
For the same price as a tooled up unit i can get double the amount of normal marines or a well kitted vanguard squad which can dish it out much more, especially with heroic intervention.
dont be suckered for the pretty feathers. Vanguard > Honour guard > Sangiunary guard.
To be honest i really do not rate dante as a pick. For the same price i can get a pair of libbys with packs.
a good start for a 1500 point JP list is:
Libby, (Sword, Lance powers) Pack 125
10 ass marines, 2 x MG, power fist 235
10 ass marines, 2 x MG, power fist 235
10 ass marines, 2 x MG, power fist 235
830 points, potential of 6 scoring units, 4 KP's, a bag of antitank and 30 troops.
leaves you 670 points to buy snackies with.
a couple basic dreads in pods (MM, HF) still leaves you 300 ish points to play with.
and for fraks sake its not a "wing".