Let me describe PCM/LPCM and the lossess codecs in some detail and how they relate to HDMI. Sorry for all the detail if you already know this.
First, most people use PCM and LPCM interchangeably. The L stands for "Linear" and deals with how the sampling is done. Although it is possible to have PCM that is not Linearly sampled, in most audio situations the signals are sampled with linear quantization. The difference does not have to do with whether it comes from a lossless decoder or not.
LCPM is non compressed format and is often found on BR disks. It takes up more space on a BR disk than the compressed lossless DD or DTS formats. But it can be sent directly over HMDI 1.1 or later and almost all HDMI receivers can handle it. It does not require a DD or DTS decorder.
The lossless DD and DTS streams are compressed (without loss of data). The decoder decompresses them and converts the signal into LPCM, which should be identical to a LCPM tract on the same disk, as long as secondary audio is not involved. This decoding can be done either in the player or in the receiver/processor. This LPCM from a player decoder can be sent over any HDMI (1.1, 1.2 or 1.3)
HDMI 1.1 or above can handle LPCM from either the lossless LPCM track on the BR disk or from the lossless decoders. HDMI 1.3 is requried to bitstream the compressed lossless DD and DTS formats directly to the receiver/processor.
So, for most processors/receivers that have HDMI 1.1 or 1.2, you can use a BR player that decodes the lossless DD and DTS formats and sends the LPCM stream over HDMI. You only need 1.3 if you want the processor/receiver to do the decoding.
Russ_I. I think you are correct that the McIntosh processors only use HDMI for video. Not sure if there are other high-end producers who do this or not. They are defintely an exception to the way HDMI is usually implementated.