I start from the assumption that the intent of the crime, from the beginning, was abduction. That means a large enough vehicle was ready, with weapon/retraints and so forth, to prevent signs of struggle or a victim getting away, and also a plan for where to take them.
The fact no valuables were taken strongly supports this. What ordinary criminal can resist stealing cash while they're at it?
So then, if it was planned and not a fluke, my thoughts are that the perp(s) very likely knew who was in the home when he/they attacked it. Otherwise, there might have been a man or two there, which would defeat the plan.
So, to me, that means either someone who knew Suzy and Sherrill's living situation (would someone who knew Stacy know who lived in this home?), and/or some type of surveillance on the home to learn who lived there.
Then there is the fact that the abductions went ahead, in spite of a strange car being in the driveway. Again, whoever did it would want to know ahead of time who had come in that car. That, again, suggests surveillance, or following them home.
And instead of deterring the abduction, postponing it until there were fewer people home, the fact there were at least 3 people in the home seemed to encourage him/them to proceed.
That's very unusual, to want to kidnap 3 adults. Kidnapping one woman from a parking lot is one thing. So is invading a home and confining and attacking the people inside the home. But invading a home and taking away three adult women, is a whole different order of magnitude, in terms of needing to control them.
In fact, I can't find examples in any other case, of 3 people being simultaneously, successfully, kidnapped. I'd welcome examples if anyone knows of them.
To me, that says at least one accomplice, but maybe even 3 guys, so they could each control a victim.
And yet it had to be more than just a gang of hellraisers, because hellraisers make lots of mistakes, or rat on each other, and so forth.
It seems to me a very diabolical plan. If there was intent, planning, a certain amount of patience, care and precision not to leave clues. To me that says revenge, rather than, say, sexual thrills.