Italdream, I recently acquired a few reservations about the FGM, but, imo, they pale in comparison to my reservations regarding the Piccolo, Primavera and the Andiamo. Out of the three, I think the Andiamo has a slight edge, but they all have huge ceilings, huge doors and cramped dimensions. At least with the FGM, even the smallest kit, you're not getting the huge ceiling, and if you go with the 800, it won't be that cramped either.
One important thing to keep in mind- there's not a member on this forum who went with a smaller oven who was later content with their decision.
If you absolutely have to pull the trigger on an oven now, I'd go with the 800C, otherwise, I'd wait until you can spend a little more.
One other thing to keep in mind is that brick ovens tend to be a little more durable than refractory. I don't personally know anyone with a refractory oven that's failed, but, in theory, brick is a bit more durable. The brick version of the 800 tacks on another 500 bucks- that's a tough call. $2.5K for the refractory version seems pretty reasonable.
Before you do anything, I'd touch base with Robyn and see how much she paid for installation. It was an indoor install, which I'm sure drove the price up a bit, but it might be helpful to get an idea.