MT, these are my first FF's so really didnt know about size/rubber changes. I know a lot of people had issues with the XR7 ones though and is why I didnt get them.
Green... If you look at the my vid again in post 26, thats about as rough as it gets, the vid doesn't give it justice believe me. 1.5hrs or so and it really starts to hurt, I make it last job of the day. Always makes me want to take a pizz. re needing the kidney belt.
I dont think Im doing more than 5 or 6mph for the most part, a fast walk.
At or near the start of the vid theres a small bare area that gives an idea of the ant nests. Its like that all over the place, you just cant see them under the grass. Some of those nests are 4 or 5" high. There kind of different to your problems though. Ruts make both front wheels hit at the same time where as these nests every wheel is doing something different.
Ive watched your vids again and even though the prop your doing leaning forward may be smoother, there are definitely some dips or rough spots in it. Your head/body is staying fairly still until you hit a rough spot and then you push/pull/jerk the sticks. watch around the 5 sec,14 sec, 24sec, 27sec in the leaning forward vid you can see your hands move.
In the other vid of you and ya miss's, its the sitting back in the chair thats flinging you forward and again, jerking the sticks. Like Ive said, you have to sit forward, let the machine rock underneath you. Watch these guys heads/upper body. Especially the second guy. It barely moves. http://youtu.be/LdeKwafcL50
or better yet... http://youtu.be/_fWt0tlfBMg
Basically, thats what you need to achieve.
You shouldnt need to lean fully forward all the time, just over the areas you know are rough. Granted, the flex forks may be making it worse for you but Id rather have them, slow down on the bad props than get beat to death on every lawn. But thats me!
The only jerking I get is going up steep rough slopes but even then its rare now. I have the drive pretty much down pat, I have a 150hrs on this SZ. It still happens, just not often. I have to drive up a fairly steep, rough track just to load up the mower so is something I learnt pretty quickly. The only other time it happens is if I forget about a bad rut or hole. Not often as I know my properties pretty well.
I just watch a few vids I havent published and while I was going pretty slow (very long grass) I noticed when I did get rocked, there was no jerking of the sticks and Im able to nullify the body rock with my legs. I hold the sticks very low at the first bend. Thats less leverage on the sticks. Higher up is more responsive if that makes sense or need a lighter touch the higher up the sticks you hold them.