Ambassador - by Irwin
Emissary - by Premier Seating
They're the same model, just made by different companies.
I was wandering if you need stadium seating to use these seats?
They're 42" high backed, so would this be blocking the person sitting behind one, or can they be used on a sloping floor?
I really like the look of these seats.
Any feedback will be appreciated, but people who know these models are mostly encouraged to help me out!
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Andrew McCrea
"I'm Not Bad, I'm Just Drawn That Way!" - Jessica Rabbit
Most models of seats are able to be modified or ordered for any slope of floor or riser mount which is how they mount seats in stadium style sometimes.
Editing: Ian, are you following me around the forums? 
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Andrew McCrea
"I'm Not Bad, I'm Just Drawn That Way!" - Jessica Rabbit
As for the Irwin Ambassador, the pictures show that the standard is floor-mounted and the Showcase Cinemas auditorium they show is a sloped floor.
I would say that with the right floor slope, you can put these in either type of auditorium, as long as your architect has done a good design job (floor slope, screen placement, etc.)
And yes, you should use a qualified architect (experienced in cinema design), even for a remodel. He will be able to determine whether the items mentioned above will work in a particular situation and how these items fit into local building and accessibility codes.