What are the pros and cons of running a Putz. in Econo-gear mode? Is there really a noticeable fuel savings? Any info./tips would be greatly appreciated.

I've used it on my Putz 36Z (2002) a few times. I have found that it doesn't work well for low slump and/or difficult mixes. I do believe that, in my case, 7th gear is the best for pumping unless it is a perfect mix. I will say that econo- gear is great for washout as it is quiet in comparison to 7th gear, but your water pressure will be slightly lower through your washout hose.

If you have consistently good mud and you can pump with it 75% of the time, then yes, you'll see a big difference in fuel savings.  I didn't have it for a while and got a pump with it and was able to use it 90% of the time (Kansas City has gravy for mud).  Saw a huge difference in the amount of fuel I wasn't using.

But like the other post said, you'll loose that extra grunt if ya need it.

We've used econo gear on our putz machines nearly 99% of the time.  Even with low slump mixes, unless you're pumping fast, we've never had a problem.  The only time we use the second from top gear is for large volume pours when we're placing 70+ yards an hour of 3" slump or less for the entire day.

The truck might sound like its working, but its still using less horsepower than if you were driving it down the road at 60 mph

Your water pressure, pumping volume, boom speeds or anything hydraulically related should not change between the top two gears provided you max out the rpm.  The max rpms (about 1700-1800 in second from top and 1250-1400 in top gear - check the plaque on the doghouse) should both result in the same driveshaft speed to the gearbox.

You will notice that the pump will not stroke when in second from top gear if the truck is at the 800rpm "idle".  You have to rev it above 900rpm to get enough flow to get the "900" valve on the main hydraulic manifold to open and allow stroking.  The flow rate through this valve is enough at the 800 rpm idle in top gear to allow the pump to stroke as the driveshaft speed is higher. 

thanks for all the advice guys, I have been using E-gear the last couple days, fuel economy is definitely improved, and engine noise is greatly reduced, I think it's safe to say that I will be using it on most jobs from here on out. Question... I notice that Putzmeister has a patent on E-gear technology, what exactly is the difference between running a Putz. in tenth gear as opposed to any other brand of pump?

The econo-gear is basically the addition of a microswitch on the transmission that tells if the transmission is in top gear or second from top (I can't remember for sure which gear position the switch is on, but I believe it detects the second from top gear).  The engine control module then limits the max rpm at whatever level is safe for the hydraulic pumps depending on the selected gear.

 
You could put another make of pump in top gear, but if you max out the rpm, you'll over speed the pumps and cause whatever caststrophic damage. 

I suppose if you figured out a way to set a max engine rpm, you could in essence make your own econo gear.