While flying the Channel 1 SID from SNA; the flight crew of a G-II received a TCAS RA with respect to a Bonanza traversing the departure corridor utilizing flight following.

Narrative

I was departing on Runway 19R. I was assigned the Channel 1 Departure Procedure but; just prior to take off; the Tower re-assigned a level off altitude of 4;000 MSL. After departing and leveling off at the assigned altitude; it was evident that a Bonanza at a 10 to 11 o'clock position at 4;500 MSL would be an issue. ATC assigned an immediate heading change to 220 to avoid the traffic. In the turn; the Bonanza traffic became a TA; then an RA and just as quickly was no longer a factor. The Bonanza traffic appeared to be on flight following with TRACON. Why would TRACON or even the Tower allow jet traffic to depart and follow the departure when there is known traffic crossing the path of the departure procedure with numerous jets departing John Wayne airport? Even with ATC calling out the traffic for visual confirmation; a clearance still has to be obtained to depart from the clearance unless a 'resolution advisory' is experienced. The idea behind a departure procedure is to expedite the flow of traffic; and it would have made more sense to assign a substantially higher altitude than one which puts low performance aircraft on top of high performance aircraft. Poor coordination on the part of the Tower and Departure Control were the direct cause of this resolution advisory.