First PBX after doing cloud for 6 months.

I work for a long time PC repair/contracted IT company and have piloted a VoIP program that has been somewhat successful. We signed up as a white label reseller from a company named Telcentris, with the PortaSwitch/PortaBilling softswitch. After 6 months and 10-15 clients struggling with Cloud hosting with constant NAT, call route, etc. issues we finally decided to experiment with a Elastix/FreePBX PBX.

All I can say is, if anyone else is in this position I assure you this is the way to go. Every single nagging issue with the cloud hosted PortaSwitch have been alleviated and all the features we could not offer, simply work.

My question is there any other general advice you'd give as far as setting up PBXs with white-labeled SIP Trunks that you'd have to offer to a beginner in the field? Is this the best route to take or is there an even better solution out there? Our clients are no more than 50 seats if that makes a difference. After finding FreePBX/Elastix from this subreddit I assume there's more I can be doing to make this part of our business more profitable and scaleable.