I had the same DSC system installed in my house 3 years ago (except for the wireless zone). I used Envisalink for a couple of years. It performed well. I had the PC1616 keypads and really did not like them. I decided to replace them with Amazon Fire HD pads. In the process of converting to the Fire pads my DSC board fried. I don’t think that I had anything to do with that. But it was ironic that I had just decided to switch to the Konnected system. There are several pros and cons to Envisalink vs. Konnected. A quick search here will give you plenty to read. For me (and opinions will vary), I found it much easier to get my Konnected system up and running and fully integrated into ST versus the process to get Envisalink integrated into ST (see this post).
I love my Konnected system with the Fire HD pads. I use Webcore to accomplish lots of things with my alarm system that I just could not do before. Nate Clark is the owner of Konnected. He and the Konnected community are very helpful.
My wife will tell you that I am ALWAYS breaking things that already worked correctly. 