I have no experience with ATI however I do have a PT1911 and I do enjoy it. It is accurate and dependable. Feeds anything I give it. However it is heavy, I usually OC my compact RIA as it is noticeably lighter for long days carrying.
An aluminum frame would help with the weight as will a belt designed for carry (a good carry belt made a big difference for me) but with aluminum you might worry about longevity.