Nova or Nova based always has the best quality. OS is nice, but i don't think they would be as reliable/durable as Nova.
RB and Nova would be nice. Picco's quality is not very good. I just read a thread about someone got the Picco Red dot blew up. Nasty!!! Definitely No on Picco.
Between RB and Nova. I would get Nova Flash.
http://www.rc-toro.com/product_info....b013d5100386ad