Here it is a couple of weeks later and I've spend several thousand and 40+ hours and I've got... NOTHING. Well that is not quite true. I have a first class education on how a closed center, radial pump destroke enabled, 2550 PSI standby pressure, john deere hydraulic system operates. I now own a $2000.00 flow tester, 6 500 PSI gauges, $300.0 worth of diagnostic tees, dozens of plugs and caps, a spagetti pallet full of hoses, $250.00 worth of new hydraulic oil, and every applicable John Deere manual I could buy and read.
I did not need to buy and install a $6000.00, 3000 series pump. I did not need to buy and install a $3000.00 complete control valve assembly. I did not need to buy and cylinders. So I guess I'm ahead. Both of them work perfectly, in fact the pump worked above spec.
As near as I can tell, these machines are just under performers. Could John Deere have inflated the specs to make a sale ? Naaah, they wouldn't do that.
Funny thing though. The 710 G has a pump that puts out 5000 PSI of pressure, about double what mine does. Yet it only has 30% more lifting power. Double the hydraulic pressure should result in double the force. The fact that it doesn't tells me that the 710D was never able to do what the chart says on 2550 PSI. So mine has 40% less lifting power than the chart, which is amazingly close to what it should have if doubling the pressure gives you what the G model has.
The machine is SO HEAVY. It is clumsy to use and is not agile. Because it is heavy, it masks the power it has, so even though it may be digging as well as a 410 (which I havent put it directly against yet) it feels slow and doggy and underpowered. If I could put on 410 sized buckets it would help a lot because the geometry would be much better. I may figure out how to do that, it could just be a matter of machining undersized pin bushings.
Final word. I'm going to turn up the pump to 2800 PSI. 300 more should help the power, but makes operating it very abrupt as its designed to move at 2550. It will be bypassing in swing and boom down, but that is just too bad. If I could I would crank it all the way to 3000, but then it would heat up and wear out quickly as every thing will be bypassing.
Thank you to everyone who responded, a lot of your input was right on the money.
If I can find a nice 410G I'm going to send this one down the road. Good luck if you own one.