Full write-up about seats was done last year after installation for my time attack event in NJMP: http://www.m3post.com/forums/showthread.php?t=374157
Yes, the airbags light came up when I installed the seats. I purchase the Occupancy Sensor bypass module by EAS. It is definitely worth it as the airbag error is very annoying on your i-drive. Also, the airbag error is caused by the missing side airbags from our OEM seats. The Occupancy Sensor bypass does not render your steering wheel airbag useless. It is still fully functional. I can say this because my car is no longer with me, I got into an accident back in January, a pretty bad one and all the airbags that were supposed to deploy worked fine. I walked out unscathed, sad story - but I can go on about it another day.
The Recaro Profi SPG is by far the best mod if you spend 8-10 track days a season like me. I removed the seat prior to selling it and now the seat is back on my GTR. Seats worked great with 3-pt seat belt and it frees up a lot of space for the back seat passenger as the seat is significantly thinner.
I can go on but I don't want to lead this thread out of topic.