Before you read this just remember that it is NOT intended to start a" whose eng is better argument."

The da has 20cc over the zdz eng. From adding up your cost to outfit the DA to what you have now works out to close to a thousand dollars difference between the two engines.

The zdz seems to be turning aprox 400-500 rpm less than the DA on the same size props. (this comes from different threads and pilot info shared here on UNMODIFIED props and no tuned pipes)

The zdz-80 is lighter than the DA. I personally have not seen a DA 100 run so i can't comment on the vibration levels of this eng. But seeing that it is a twin i will assume that it runs very smoothly. My personal experience with 2-ZDZ-60's and a 80 is that the 60 has very little vibration. The 80 will shake the plane if the idle is set to low. Other than that, it runs very smooth once the needles are set correctly.

I guess if i was given 2 engines at the TOC i'd run them no matter what the make as long as they were reliable.
All those pilots put in a tremendous amount of flying during the season so parts availability and close factory support have to count for something.

I guess my point is, if you want a twin and can afford it go for it!! If you want a engine that is 20cc shy of the twin but is lighter and only down a few hundred rpm from the DA and aprox. $1000. dollars cheaper then go for the ZDZ!!

I guess it comes down to what you want more.

ttyl