Wow, this is great news for me. Thanks.
Ideally I would like to have 3 to 6 nodes in a tight group and then splice in say 6 feet and have another 3 to 6 nodes in a tight group, splice in another 6 feet another group of nodes, etc.
What total length (ie feet) could I run before I potentially get in trouble?
There are two things that you need to need to watch out for with smart strings, signal loss and voltage drop. As RJ said, you should be able to go about 10 feet between nodes without signal problems but if you need to go farther or for some reason are having issues, you can simply add a node in the middle of the length and simply skip it in the sequence. Each node recreates the signal minus the channel it claims for itself so you can add nodes to increase length as long as you have the channels available for them.
Since we are using 12V for smart strings, voltage drop is not as much of an issue as it is with 5V strings. Before I would get to worried about it I would set up a test and see if it is even noticeable. Since you are using groups pf pumpkins, even if one group is a little dimmer than the other, it simply may not even be seen. If it is, you can correct it by either slightly dimming the group that it the brightest in the sequence, use a heavier gauge wire between the groups, or inject new power on the dimmer groups.
Rather than splice and solder in the 6 feet between the group of nodes, could I use connecters of some sort (molex?) and then make extension cables?
There is no reason not to do that except for the cost of the molex connectors. Just make sure that they are either outdoor rated or protected from corrosion or you could have issues with voltage drop and signal loss.
