I have spent time testing VU VST's. I have tested them all. The Sleepy Time VU although free is not bad. It will show the correct levels etc
(with sinewave calibration test signals) but the ballistics of the needle movement is quite wrong compared to something like the Klanghem meter for example. Ballistics is super important. eg the way the needle dances to the music. It can tell you a lot and if the ballistics are a bit wrong then the meter becomes much less helpful. I have devised some complex tests for testing ballistics.
I have real VU's and expensive
(a decent VU meter can cost around $200!) high end ones at that and to be honest the ballistics of the real thing are very hard to beat. If you think about ballistics, it is something that is not simple to do. It is quite a complex thing to emulate in fact. The way the needle accelerates up towards 0 dB VU and how it falls back too. The way it sways back and forth etc..
The PSP meters have reasonable ballistics and so does the Klanghelm meter. Klanghelm a little closer to the real thing. They have spent some time on it. It is worth the price of admission as they say.