Opinions wanted on Wheel adaptors, are they safe?

[BBC69Camaro]

I'm looking for opinions on wheel adaptors (not spacers). If they are safe / don't cause any vibrations or issues with changing the load on the suspension etc.

Example:
http://www.skulte.com/product_info.php/products_id/58

This would be 90% a street car (with occasional track use). The suspension / brakes are completely redone: GW uppers/lowers/coilovers/c5 brakes with AFX spindles, g-bar/mini-tub/12" discs in the rear and because of that I don't want to have to worry about breaking something either when I drive it hard (which I know I will do).

The reason I would need to run wheel adaptors in the first place is, I want to run the Wheel Vintiques Billet Rallyes (series 90) on my front C5 brakes from Touring classics. I know they won't clear. I haven't measured yet but I probably need a 3/4" to 1" adaptor to clear the caliper / brackets.

This would be the look I am going for (not my car 'shopped):


I am kind of going for that sleeper look and really just want to run the rallyes, I have looked at so many wheels that will fit the C5 brakes, but I still just want/love those rallyes

Thanks in advance