I installed an older True Fit in our 07 Rondo a few months back during my cert. class. It seemed to be installed well, but I was still pretty new with installing seats, so I'm not sure if it was in there totally right (our instructions had never installed one either and I don't think they looked at it too hard). As for the MR, I wouldn't see it being a problem. I'm getting together with a friend of ours this weekend that has a Nautilus. If you haven't gotten any replies about that install before then, I'll make sure to let you know how it fits.
As for the Rondo... It would work really well for a family of 4 as the previous poster mentioned. Over 2 kids and you lose all the extra room in the back. Also, there is no tether in the 3rd row. All that aside, we LOVE our Rondo. I only have the one DS, but do take other daycare kids in it quite a bit. I've been able to install an EFTA rearfacing in the 3rd row, but it's pretty upright. We usually use it for 2 boosters when I have a car full. There's a lot of room in the back with the seats folded down and all the seats I've tried to install in there have gone in pretty effortlessly.