TL;DR:

• Vanguard changes haven't stopped pirate BS blitz fleets in highsec but have hurt 'regular' highsec pickup fleets and lowsec HAC/T3 fleets
• Increasing Vanguard payouts by 10% would bring highsec blitz income close to previous levels while not appreciably helping other fleets
• Assault changes missed the mark - problem was and remains the NCN sites, not NPC grouping or difficulty
• To make assaults more attractive, reduce number of rooms in NCNs and allow Command Ships into the cruiser rooms

Wall of text:
I disagree with the claim that the Vanguard changes have somehow stopped blitzing; if anything, they've significantly increased the gap in earning power between pirate BS-heavy blitz gangs and other fleet types. Highsec pirate BS blitz fleets now get through sites in 4-6 minutes, while both 'regular' pickup fleets and the HAC/T3-heavy fleets that were most commonly used for lowsec incursions now take 10 minutes+ per site. This is largely due to the Override Transfer Array sites - while pirate BS fleets can punch through the NPCs' reps without needing to hack, other fleet types cannot. Reversing the 10% income change would bring the blitz fleets' income close to pre-nerf levels while not really helping other fleets all that much. Ultimately, I don't think it's going to be possible to prevent players from min-maxing fleet compositions and tactics to minimize site completion times unless you're willing to introduce some kind of hard lower boundary on site completion times, such as a boss NPC who only spawns after a specific amount of time has passed.

As for assaults, I think your comments and changes both miss the mark. The main source of complaints, before and after the changes in Escalation, was that the Nation Consolidation Network site is a giant pain in the ass, being much slower to complete than the other two assault sites and requiring a much more specifically-tailored fleet composition. You didn't really do anything significant to address that, and the changes you did make had little impact on running assaults one way or the other. If you want to make assaults more attractive, you're going to have to do something about the NCN. Ideally, this would be done by having only one cruiser-only and one BS-only room before the final room in which the fleet re-unites, with an increased number of NPC waves in the two rooms where the fleet is separated. In addition, I would encourage you to allow Command Ships into the cruiser rooms, since they are more useful than most cruiser hulls in the other assault sites, and so would make it less of a drag to get an NCN-capable fleet together.