I have tried using the MI3125B quite a few times. I must admit that I do not test on a daily basis as my job is working at test-meter, but I normally try out new products that appear interesting. I know that the design is different from other well known testers (other Metrel testers, Meggers, Flukes, Kewtech etc..) and I guess personal preference always plays part, but I found to be easy to use. It has a magnet on the back of the meter meaning that it hangs from any magnetised surface which means that you have both hands free. The Easi Switch which was launched with the MI3101 EurotestAT also works with the MI3125B (please note that there are other Metrel meters with the same part number like ComboLite and MI3125 Combo T - these do NOT work with the EasiSwitch or store/download test results). This does take headache out of rings mains testing and makes the job a lot quicker, so that is in my opinion a welcome feature. The specifications of the MI3125B are quite good as well carrying out all the tests required for TN and TT systems and it includes the RCD test for type B RCD's. All in all I can't really fault the product from having used it.
If I could say anything negative it would be that there are too many Metrel testers or Multifunction tester kits with similar part numbers. I haven't often found customers confused by prices and differences when looking around. If anyone has any questions, please let us know. I think we have finally gotten our heads around all of them now ;-)