When you say "rear outlet", is it hanging off the wall and dangling above the floor? Or is it standing on the floor but you know that the discharge is from the rear rather than into a flange on the floor?
I have no knowledge or experience with the toilet you mention. But beware: "European" doesn't necessarily mean "good". The spec sheet from Signature is worthless; it doesn't even say whether it's a gravity toilet or a pressure assist. If it's pressure-assist, the pressure-assist dual-flush units we have seen are garbage. If it's gravity, I'm a little concerned about that 2" flush valve giving you enough oomph for a decent flush. Most of the rear-discharge units these days are pressure-assist...for a reason.
There was a pretty good thread on this regarding floor-standing rear-discharge toilets, including a few recommendations of products, just a few days ago...let's see...okay here it is:
Look at posts 9-13 for the discussion of the merits of certain models, including the Gerber one you can see where the poster said "This is the one I'm looking at". Click on that for the spec sheet on the toilet he was thinking of (and which we told him to get in the 1.1 or 1.6 but not the dual-flush). Terry's post with models he has experience with is like number 12.