Looking for some pointers. Migrating from Elastix 4 to FreePBX 14

Here is my current setup, I am running Elastix 4 with about 10 or so extensions (a few Grandstreams phones and a handful of Bria clients on iphone and iPads). In addition to this, I have a Digium 410 card with 2 FSX and 2 FXO cards. The Digium card is connected to my 2 POT lines (home line and work line). At a remote location, I use the OBI202 for making the 2 POT lines available. The OBI connects a 2 line Analog phone to 2 extensions (600 and 601) which map to the 2 POT lines at home.

4 trunks (2 Dahdi) and 2 SIP. 4 corresponding Inbound Routes and 5 Outbound Routes.
Specifically, 2 of the outbound routes are for the POT. Extension 600 maps to the House Line and uses the House Line trunk (DAHDI Identifier 1) and Extension 601 maps to the Business line and uses the Business Line trunk (DAHDI Identifier 2)

In my current setup, I was never able to get the callerID on call waiting to work on the remote location. I was never able to get the hook/flash to work on the remote location (i.e. to switch to the other call).

([[email protected] ~]# rpm -qa | grep dahdi

I am looking to migrate/re-implement on FreePBX 14. Any suggestions/best practices? Should I abandon the Chan_SIP and embrace PJSIP? Being new to FreePBX 14, are there any other configurations/options I should consider?