You should have no problem towing with the D4, even in the D3 I have to keep looking in the mirror to make sure the vans still attached, with the extra power/torque afforded by the D4 the 560/4 will seem like a lightweight. I want to upgrade to a D4 next year (hopefully!) for the reasons above and the better fuel economy and lower road tax.
On the motormover/shock absorber issue, my EGO is fitted in front of the axle but still has plenty of room for the shocks (did I say you need the Red Octagon shocks, for the 560?). Once I got the wheels off it only took 10mins each side to fit (would have been less if father-in-law wasn't hovering and asking me what I was doing every couple of minutes).
We only got into caravanning about 2 years ago, bought a cheap Sterling Sprite Excel 2 berth which got us hooked. Then early last year we just missed out on buying a 560/4 2009 at a Lincoln dealership (literally by minutes), the wife (having spent hours/days/months researching) was convinced the 560/4 was the perfect layout for us, and after a late night searching t'internet found our 2008 van for private sale in the Beccles area (a 300miles round trip). So 48hrs later after the longest day trip ever, we were the proud owners of a mint/like new 2008 model (only runout 3 times previously since built, and fully loaded with awning. and all the extras including satellite dish/receiver/tv). I'd only ever towed the little Sprite about 4 times previously (and we only had a RAV4 SR180) so the 560/4 seemed like an artic trailer to me, especially as I hadn't mastered reversing then, what a trip back!
We love the 560, and hope to keep this one running for some years to come, as our trips with the three dogs (together with the extended family kids sometimes) have proved to be the best adventures yet.
Happy camping.