Can we check whether there is any links or KB for us to take note when we migrate from 3rd party SSL VPN to Juniper MAG?
There is nothing for moving from another system to the SA ecosystem; however some things to keep in mind could be the following (I personally have not seen any other system, but am guessing there are things similar between the SA & other systems):
IPs for the system
groups/rules for role mapping
bookmarks/access provided through non-L3 VPN options
IPs used for VPN tunneling/L3 VPNs
rewriting rules (if applicable)
any special actions needed for the rewrite equivalent to work (for example if a custom web app needed special rewrite items, pay special attention when making the move to the SA)