I can't recommend the FB ovens for NP pizza for a home environment. The main issue I have with it is that it cooks unevenly IMO. Meaning the floor gets much hotter than the dome, when you have a big rolling fire overhead. Consequently the bottoms of the pizzas burn easily unless you do half of the cooking off the floor and on a peel. This issue was discussed in the CY dough thread.http://www.pizzamaking.com/forum/index.php/topic,21730.msg239181.html#msg239181
You can get by if you are only doing a few NP pies or make NP once in awhile, but it's a pain in the ass to do that. I don't know if that also holds true in real NP ovens or not, but I imagine it doesn't happen as often, especially if the oven is fire properly and saturated.
Now you can probably get around this issue by using Whitacre Greer FB as member Shuboyje does in his WFO's, but you'd have to factor in the cost of a new floor. Likely not that pricey. There are other tricks you can employ as member Pizza Napoletana has done like using a metal plate to sit where you will bake your pizza until you are ready to bake. Then remove the plate and the floor is cooler. BTW, Omid does not have a FB oven, but I think experiences a similar hot floor issue.
But if you are going to be doing mostly NP pizza, I think it's worth it to pay the extra $ and get a real NP oven. Especially if it will be the one and only oven you will ever buy. The FGM oven seems to be gathering quite a following here on the forum, so I would look into that oven as well. But before everyone gets too excited about it, I would like to see more of the advance members bake in the FGM oven and see how their results compare to their own ovens. I know member JCONK, who makes beautiful pies recommend the FGM oven.
I will also say that if anyone is interested in a wfo, you may consider getting one that is bricked dome or bricked lined on the interior. They are just more appealing to look at when you have a nice fire going rather than refractory cement ceilings.