Is is wise to set Power Conditioner on its front rather than on it's bottom.

I just purchased a Core Power Equi-Core 1800. Wally said he saw no problem in setting it behind my rack on the front with the outlets facing up. Obviously, I would set it on  footers. But this thing weighs 55 lbs with a big toroid transformer in it. While I know it will work, I'm concerned that this heavy transformer will come loose due to gravity and from there vibrate thus causing noise. For those with experience or more understanding of how this unit is built, what are your thoughts? Good idea or bad? Thanks 
arte