We use RadiusManager without problems.. only they have to fix the csv export but works fine for us.
I need that someone who used Radius manager and now uses usermanager tell me why they changed.
With usermanager you can log all the user connection? like the CTS of Radius Manager?
I prefer UserManager above any other FreeRADIUS based product (or any other RADIUS product for that matter). Using FreeRADIUS with eg Dialup_Admin, you need to do lots of customization to fit your needs. RadiusManager is great, but when you run into problems its slightly more advanced to repair. Many people don't have Linux skills, neither coding skills to customise it to their liking.
UserManager is a great product, very little customisation needed. In order to pull reports and add extra functionality, you could write scripts that does everything for you.
Have a look on the Wiki for Krige's usage notification script, it's a GREAT example of what could be done for UM.
I myself wrote my own version, based on Krige's script, but customised to my needs. I even wrote an automatic invoicing system, running on RouterOS together with UM. It took me about 7 hours to write the initial part of the Accounting part of the script, so there might still be some bugs (none yet) and now I can customise it to MY needs. Once I'm done tidying up the script, I'll put it on the Wiki. (I used the part of Krige's script which calculate when a user reaches 50%, 75% and 90% of his CAP, and added >100% of CAP so my Accounts dept get an e-mail when a user gets CAPped).
Yes, with RadiusManager this is also possible, but, what do you prefer, a system which works great until you run into software or hardware problems and having to reinstall from scratch, difficulty importing backups etc (not too difficult, just more advanced), or a package like UM, where you can receive daily backups via E-Mail and IF you need to reinstall or replace hardware, you simply restore a backup, import your user DB and install your scripts again.
Just my 2cents