You get +1 to the roll to see who goes first if you deployed first. My friend and I looked in the BRB and we couldn't find anything in the BRB that explicitly stated that scouts don't count as part of your deployment for those purposes. I think the spirit of the rules is that scouts don't count as your normal deployment so you get the +1 for having the first turn if you finished your normal deployment first and then deployed scouts. But by the literal wording of the rules it seems that deploying scouts counts as being done last if your opponent had no scouts.
there is a ruling about this in the ETC rules (not the official GW FAQ) saying that scouts do not count. but afaik, there is no proper ruling about this from GWs side. however, i have never met anyone who didnt agree that scouts should not count.
We had the same problem, so we found this in the Brb. On p142 -Deployment -alternating Units: "All characters must be deployed last" Thus the deployment phase ends when characters are deployed, and then you set up scouts. So you do get the +1 when you finish first with your characters.
Nice find there. This has come up on the forum before. That is the first thing that has supported the argument that scouts do not count toward deployement.