If CG Pro indeed does good metals, I would go with them. I have had many canvas prints done by them and was happy with the quality. But never had metal done.
So, like you, I can only go by what others say. However, if they are good, their pricing is usually lower than competitors.
For example, using the open / raw online prices, Adoramapix asks $74.99 for a 16x20 where CGPro asks $49.99 - a substantial difference.
My problem with CGpro and why I have never had a metal done there is their limited sizes. For example, if you're shooting a standard 2x3 format, the very first full frame metal size CGPro offers is a 20x30 which is rather large. I've inquired about them adding additional sizes, and they reply it will be done, but nothing has changed is the last 2 years.
Nonetheless, if you're printing standard sizes and can work with CGPro's limitations, and if their metal product is good, because of much lower prices than many competitors, I would go with them.
Let us know who you choose and how the quality was.