I apprenticed at a brewery that had a very nice 20 bbl Newlands system. The plant was steam fired and equipt with a seperate whirlpool vessel.
The brewery production was mostly ales. I was there during ramp mashing for a wheat lager.
The system incorporated a large transfer pipe (3 or 4 inches in diameter) between the kettle and the mash/lauter tun that was used to transfer (pump) mash from the kettle to the lauter. The mash/lauter was insulated but not heated.
One fault of the system was that the transfer pipe would fill (pack) with grain during all mashes (ales) and took longer to CIP the system. I thinl that the system would have been better if a jacket or steam injection system was added to the mash/lauter tun to eliminate the need for the transfer and cut the amount of time required for the CIP. I own a small 3 bbl system (that is not currently in use) that has a jacketed mash tun.
The Newlands system had a good rake/plow system, underlet piping and a bottom cleanout hatch. It did seam to be a compromise design.....but it makes good beer.
Decoction, never touched it on a large scale. I really do not see the need. It would require more equipment = floor space. Would the end result justify the expence? or would a more highly modified malt work better.
Hope this helps.