Richard,

Zeton was a pleasure to work with.  They really strive to meet the customer's needs and I felt that customer satisfaction was their primary goal.  As far as your specific questions:

1.
A. Zeton provided us with a firm quote for the original scope of work.  We changed the scope numerous times as the project was being built and Zeton provided us with change orders for any excess work outside their original scope.  If there were any discrepancies or disagreements on change order costs, Zeton would not bill us for those until we mutually agreed on the charges.  At the end of the project we reviewed all of the change orders charges because I was able to show where they replaced something in the original scope of work.  So I feel Zeton was very budget conscious and performed very well in light of all of the changes we made.
B. Zeton provided us a firm schedule in the original bid, but due to conditions in our company at the time, it became urgent to accelerate the schedule.  We negotiated with Zeton to pay extra overtime for some of their shop workers and pay expediting costs to receive some of the equipment sooner, and they were able to cut the schedule in half.  They delivered the unit on time and really jumped through hoops to help us get it started up on our schedule (which was approx. 3 months sooner than their original estimate).

2. 
I would have allowed Zeton to provide more input in the original project design.  We used an outside consulting firm to provide a preliminary design to be used to bid the project.  This company had no experience in pilot scale plants, and had a lot of unnecessary equipment in some areas and not enough in others.  This caused us to have to make many changes to the original scope after the project was bid.

3.
Due to the extreme vacuums and high temperatures we ran on the distillation unit, we had a very difficult time with our level transmitters on the distillation unit.  We ended up changing to a remote seal type DP transmitter to solve this problem.  This instrumentation problem delayed the startup by about 4 weeks while we tried to solve it.  Zeton worked closely with us on solving this problem and gave us a credit for our costs to replace the transmitters.

4.
We have used other pilot plant manufacturing companies on larger scale units, and in my opinion Zeton provided much more support from beginning to end.  Even two years after we started up the plant, I could pick up the phone and call Chris Brown and he would always answer my question I had or tell me where to order repair or replacement parts.

In general I would highly recommend Zeton to anyone building a pilot plant.  They take a personal stake in every plant they build and will always bend over backwards to satisfy the customer.