Don't be afraid to keep running with it. I'm planning to morph the gateways into the League and cutover when AM isn't required anymore.
The biggest issue is that AM doesn't support recurring payments in any way. I didn't realize that when I started. So I've been augmenting their structure to make it work. I pulled it off easily with Braintree, but when I got into PayPal I realized that AM's method of sending API calls to PayPal was dated and I've spent too much time working on the recurring PayPal piece. I could have built it from scratch at this point.
I mostly want to cut my losses and bring the entire gateway process internal to the League so I'm not dependent on other gems. If I do that now, there's more flexibility in the long run and very little lost right now.