There will be a differenc in ride between the two models. The 351 will be on Fords 22K chassis with 19.5 inch wheels/tires and the 350 will be on the 26K chassis with 22.5 inch wheels/tires, same size as trucks. There will also be alot more basement storage space with the full basement 350 with at least three pass through compartments (some rigs have none!). I don't know if it is a fair comparison but my older Allegro had the small chassis tire combo and I can not believe the ride difference in the larger combo on my 330TS. Dishes don't rattle in the cupboards nor do you get any creaking sounds from the interior of the rig as a whole.
As far as the inverter set up goes, I am sure there wll be more responses from those that already have them. They started out being only found in higher end or DP but now it appears they are creepin down to the mid level rigs. I see it as another example of Forest River trying to give you the most bang for a modest buck in comparison to other mfg's. One thing I would look for though is that the inverter set up has an automatic transfer to the generator that if the battery levels drop to low the genny will automaticallly start up to recharge the batteries. Can't see the system being that good with out that feature, especially boon docking or long days on the road. Good Luck on your decision and keep us posted on what you decide.