Instead of 9.Qb3 I would prefer 9.Re1 or 9.Bf4 intending perhaps a3 and b4. Similar positions can arise in the Nf6-Scandinavian: 1.e4 d5 2.exd5 Nf6 3.Nf3 Nxd5 4.d4 Bf5 5.Be2 followed by a later c4. In "Attacking with 1.e4" John Emms evaluates these as slighty better for White.

Also after 5.c4 Qa5+ 6.Bd2 should be considered. If 6... Qb6 then 7.Bd3!? looks interesting.

After the end of the Ikaria Open in Greece, we discussed together with the winner of the event GM Moradiabadi Elshan some positions and one of them was the 3.Nf3 scandinavian 1.e4 d5 2.exd5 Qxd5 3.Nf3. I don't like playing the Black side of this variation like many other players i know, because the complications that arise after 3...Bg4 etc are not to my taste and objectively i think White has an advantage.

Asking Elshan about this issue i got a surprizing answer! He said that White cannot claim an advantage if Black plays just simple chess! For example:
1. e4 d5 2. exd5 Qxd5 3. Nf3 Nf6 4. d4 c6
i know that this was recommended by Im Martin but Elshan doesn't believe in ...Bg4. "Simply ...Bf5!"
5. Be2
if 5. c4 Qa5+ 6. Nc3 Bf5
5...Bf5 6. O-O h6 7. c4
if 7. Nc3 Qa5 and we have a comfortable line for Black. The c4+d4 centre is the only reason White plays this
7... Qa5 8. Nc3 e6 9. Qb3 Qb6
"and Black is OK", Elshan

The idea is simple:
-Put the bishop on f5 and play ...h6 so that Nh4 will not be a problem
-if c4 play ...Qa5 and if Qb3 play ...Qb6
-play e6,Be7,O-O and put pressure on the d4 point

My question for the scandinavian exerts here is:
can we trust this position for Black? Do you find a specific drawback to it?