I also run britax as my whole family, including 4x4Jesus has always run them and they have an awesome reputation.
As far as sitting in the front seat, I have a Tj, and I seldom even have a back seat while wheeling, so my 3 year old also sits in the front, but before I even thought of putting her up front I pulled the wires from the passenger airbag... The airbag light is always on now, but in my opinion it's better to not have it then for it to hurt her.. I did the same thing in my work van, it's only a 2 seater, so I completely removed the airbag to be positive it would never hurt her.. I'm sure I'll get roasted about how wrong that is to do, but I really don't care.. It's all about my daughters safety
05 Tj, long arm, one ton, lockers, winches, 39.5" Iroks