Apparently last week, (11 September, 2013) Turbine "brought back" "thehappycloud "as the downloader for the Mac Client. (And presumably the PC CLient as well, but I have not investigated.)
So far, I have only begun testing the "Play Instantly" On Mac option.
Thehappycloud Interface is much "cleaner" than the old PMB interface.... and one bonus -- it begins playing Chance's Riders of Rohan theme as the download begins! (Bummer, it simply loops the opening track. But that itself is a convenient way to determine that the download is still in progress.
Estimated download time on my 2meg DSL is 188 minutes (3.1 hours) MUCH faster than PMB, and I believe either equal to or faster than the Steam Download.
The Happy Cloud downloader is a 6.5Mb "pkg" download -- LOTRO_Mac_360.pkg.
Note that this downloader is different from the full Happy Cloud interface.
There are 3 numbers posted next to the "download speedometer" ...
Minimum Buffer: 2983.8 MB
Full Game: 17594.5 MB
One presumes (since I haven't gotten there yet) that the "Minimum Buffer" number represents how much of the Full Game needs to be downloaded before you can "play instantly."