I think you'll find these same issues with all the other manufacturers, you'll just find out when you're in too deep. If you think these problems are not present with other manufacturers, you might be in for a lesson learned.
I have some legacy ITI (now Interlogix) with learn mode sensors and needed to replace some sensors. When I called their tech support they did not want to help me because "the legacy product was no longer supported." They suggested I replace the entire system because their new learn mode sensors may or may not work with the CTP+. They suggested I try it to see if it works with the panel's receiver. Honeywell told me how to add a new sensor to a non QED panel some years ago.
I have some accounts using legacy DSC products and I'd rather scratch my eyeballs out than try to remote to those systems with their DLS. I have legacy Napco panels in the field and their Quickoader software is okay, but I need to remember so many things just to connect so it takes a few tries. With legacy Radionics (now Bosch), better have a D5100 programmer with you or you're not programming at the site. And, the Radionics programmer was not fun to deal with. ITI, now Interlogix, keypad programming was good with CTP+ and Ultragard. With my legacy Moose products, remote upload/download is not even considered now that their software will not work with the latest Operating Software. Since I standardized on Honeywell, I now have legacy panels of other manufacturers and not their latest products. Moose had a very good remote software in the RPM2, but that had some anomalies too.
I have some legacy Honeywell panels that use an earlier version of Compass, VIA30 for example, and I have a separate computer for the legacy panels of all manufacturers. I have no worries using Compass on these old panels. However, when dealing with other manufacturers it gets worrisome.
I too found out that adding user names in Compass does not transfer to Total Connect. I had a customer set me up as an Admin User and I added users for them in Total Connect, then had the Master User Sync the panel and the users. I tried to do this through Security Professional Access, but if you inadvertently close out the customer will need to get you back in.
I found, many times, that my call to tech support was due to my lack of understanding and failure to thoroughly read the documentation coupled with being unfamiliar with the product. Also, I find that directly emailing the Honeywell District Rep gets a quicker response than calling Honeywell Sales.
Again, I'm not saying Honeywell is better than others, I'm saying that you can easily trade one set of problems for another, and compound your frustration.