This has been a fascinating thread, and thanks to Jeff for all the helpful info, as well as to Robbyk for starting it!
Could I ask, out of interest - especially to Jeff - if you record and mix at around -20dbfs what level do you aim for for your mastered / finished product?
 
And if it's not too much hassle - these new meters now also contain a "Loudness Range". The Long-term, or Integrated LUFS might be -23db and the Loudness Range might be 8 LUs. What  does this represent and how dignificant is it? Is this the same as Dynamic Range? 
 
If it does, great. It means as a general rule we can look at LUFS as being more or less the same as RMS and Loudness Range as Dynamic Range. 
 
By the way, I too am a fan of VU meters and I have the Klanghelm - 8 Euros!! Excellent meters and I reference at -18.
 

A very good article to read on Loudness was in Sound on Sound Feb this year. Soon it will be free to download so just keep an eye on it.
 
http://www.soundonsound.c...icles/loudness-war.htm
 
Once this is free to download that article refers to some very cool links which explain the whole Loudness standard. They are also well worth reading too.
 
VU readings and Loudness readings are close but not exactly the same. But working with K system and VU metering will put you right in the ball park.
 
Dynamic Range metering and the Loudness range are also not quite the same thing. I suggest you get into a Dynamic Range Meter such as the TT meter.
 
These days I work with all three now. VU metering during the production. Dynamic Range metering and overall Loudness metering. I think you need to work with all of them at the same time especially in mastering. I like to insert the DR meter before and mastering in order to keep a close eye on the DR of the mastered sound. The DR meter will also tell you if you are squashing your mixes too much. If the reading is a little low you can go back to your mix and ease off some of the compressors that are in key positions in your mix.
 
There is a sweet spot in mastering where you can get decent loudness but at the same time manage a healthy DR reading of say 9 or 10. But once you tip over that though the loudness goes up OK but then the DR reading starts to fall to 8 and below and that is just bad.
 
In CD mastering these days I am aiming for a VU rms average of around -12/-10 db rms now which also results in a healthy DR reading of about 9 or 10 and the LUFS reading also ends up being in that ball park too. It would be nice to master a CD to -23 LUFS too but clients are still a little reluctant to do it. They still want it reasonably loud.
 
When I am producing music or soundtracks for TV though I stick to the recommended -23 LUFS standard though. The TV guys love it. They can just drop it in and the levels are all perfect.
 
The free Orban LUFS meter is also excellent and does a great job and tells you much about the signal you are monitoring.
 
http://www.orban.com/meter/
 

To Jeff....
Jeff, thanks for the PM and for the extra onfo on SOS...it is viewable now and I look forward to reading it. Apparently I need to make a few more posts before I am eligible for PM'ing people directly, hence this rather public thankyou!!
 
Thanks also for taking the time to share your knowledge...I have visited your website, listened to some of the music, and I think you're a wee bit beyond the level I am at!
 
What I am pleased about is that ever since I stopped worrying about loudness, and concentrated on getting a good working knowledge of EQ and compression my mixes have sounded consistently better, and using the K-Meter and VU meters as reference tools have helped enormously.
Jim