Hi, I don't have any experience with Redsail but if you search for Jinan Lasers you'll find at least 6 other active Chinese manufacturers.
They are all in the same Jinan area and sell the same product with slight modifications from one to the other. I have heard good things from hxlaser (Rabbit products) and wklaser, but ended up purchasing from Jinan Artsign as they were one of the first to get CE and FDA approval (required for import to the USA).
The parts they use are from the same sources, the driver board and software is used to differentiate one from another.
I am very happy with the purchase, and of course the cost savings. The support from the manufacturer is minimal although they did at least try to help with initial setup questions. The manual was in 'Engrish' but understandable and they provided a DVD with videos for setup, job creation and problem solving.
Having said that, if this machine is your primary business tool then I would recommend Epilog, ULS or Versa.