Obviously I'm from the NECO side of things, so I would love to see the events stay combined in the future as I'm a huge Contour fan and think combining our resources benefits both groups. The NECO guys loved having you guys involved and attending, it added something to this year's event having the Contours with us (even if there were only 6 of them).
I don't know how the NECO guys feel about this overall, but let me just spew my opinion at the wall and see what sticks.
I personally am not stuck in the July routine, as this was my first ZingFest, so I personally don't see why one of you guys couldn't put together something in a reasonable part of the country (i.e. not in an extreme in any particular direction) for a May/June timeframe (when was SpringZing in the past?) and try to get the NECO guys to join you guys for a year. Again, just thinking out loud, but maybe alternate who gets the event each year. CEG does a joint event in the May-ish timeframe, then the following year the NECO guys put on one in the July timeframe, then back to May, etc. This keeps it from seeming like one side is "taking over" the other, and keeps the traditions of each event alive and well. This also lets the major players on each side get some "rest" from trying to find locations/put on the event (Jaged did a GREAT job this year, but it was also a LOT of work from what I understand and he shouldn't be pressured to do it all over again next year). To that same note, if someone from the CEG side wants to put together the event next year still in the July timeframe, you have a very good likelyhood of the NECO guys getting on board and attending another combined event.
IMO, splitting the events apart again just isn't what we should do right now. Both groups are getting smaller and smaller. We combined this year and barely had 30 vehicles take part. Having two separate events for groups that have so much in common would just divide people as many of us just don't have the ability to do two separate events each year. I'm from the Cougar side, but LOVE the Contour's and combining the events increases the likelihood of me pulling the strings needed to get to the event, as opposed to just going to a Cougar-only event or a Contour-only event.