Wow, this thread has been going since 2013 and still getting hits. I found it whilst researching if I should finally relent and try MM5 Beta. Here's my thoughts.
If your a "dyed in the wool" MM user, just do it. Easily installs as a separate version leaving your current one intact. You should also note that any changes you make in MM5 will automatically reflect in MM4 once you run a rescan of your folders.
Although it has what I think are some minor bugs (I may be wrong - after just 2 days of testing it may well be something in settings), I am loving it. Need to spend some more time in testing, but it is looking like I may be happy with it and won't bother going back to version 4.
Service. You can't beat it. On one occasion with MM4, I required assistance retrieving purchased codecs and despite the fact it was some years after the "you must download by...", they did not bat an eyelid and helped me out. You don't get that sort of service elsewhere.
As far as the cost is concerned, go back to page 5 and see this post.
http://www.mediamonkey.com/forum/viewto ... 60#p458494
In my particular case, I have been a Lifetime user since 2010 and some quick maths suggests for the € 34.0 it cost me, that works out at approximately € 0.01 per day which begs the question how do they actually make money? If they turned around now and said I had to pay again, I wouldn't bat an eyelid just as they did to help me out when I needed it. I for one have certainly got my value out of the lifetime membership. Thank you Ventis Media/MediaMonkey.