apparently, the slot heights on Nautilus and Frontier and Regent are very subjective to the vehicle they are installed in. So, difference could be minimal, or quite a bit, making either one taller/shorter, depending on the vehicle. Heh. Not incredibly helpful, huh?
I've read all of your links (and a few of them are just members that have heard the GN is higher passing that info along... so not a true accounting of which is higher or not) and what we need to remember is that slots heights are *subjective*... it depends on who is measuring them and how they are measuring them.
We started using them as a *tool* to help parents choose a seat, but they definitely have flaws if you are only going by slot measurement height. Seats fit in different vehicles and easily change just how much growing room a child has in them.
The comparison thread I did shows the same two children, with all the seats installed in the exact same vehicle position installed as upright as possible (no recline features used). It shows pictures and measurements of how much time is left in each seat.
When we tell parents to compare seats, we tell them to try them in their vehicle with their child in it. It's the only true way to know how much room they actually have left. For this reason, I believe the Comparison thread to be a much more accurate depiction of how a child really fits in each of those seats.
Using the same child in the same vehicle seating position, the Frontier was .5 inch taller than the Nautilus (Jenny's comparison is showing them the same height)... I'd say that's definitely taller in my comparison, but not by much and not really enough to matter in most cases either.
The reason I choose the Frontier over the Nautilus (especially for Canadians where the price difference is minimal) is for the extra expiry time, deeper seat depth, ability to cross legs, wider shoulder area, much taller booster mode and the fact that I *know* this seat can get any child to seatbelt age... I can't say the same for the Nautilus. :shrug-shoulders:
There's nothing wrong with the GN, and for parents in the US where the price difference is a much bigger gap between the two, I can see why they go with the GN (especially since your hwh combo seats are very limited)... however, I'm still concerned that by going with the GN, parents will switch their kids over to backless booster mode sooner than they should because of the lack of shoulder room for older kids.