New user here. I have essentially configured the new 900e to match the configuration of our in place 4430. We can no longer access RTP graphs, etc, due to the netvanta still using Flash for these to display. The only difference I can point to is the 4430 having 2 gig eth ports as opposed to the 1 on the 900e. Is there anything about these 2 devices that would indicate you wouldn't be able to replace one with the other?
Both of these devices run the AOS software, so they should be very similar in function. The 4430 has much higher Ethernet to Ethernet routing performance than the TA900e line of products. You can compare all features using our feature matrix linked below.
The latest release of firmware for the 4430 should no longer have flash for the VQM/RTP graphing. Since it sounds like you have Enhanced firmware installed you will need to log into your MyAdtran account to download it.
If you do keep the TA900e in place I would recommend upgrading it also to the lastest firmware version.
https://supportcommunity.adtran.com/t5/Total-Access-900e-Software/ct-p/sw-ta-900e