How important is HD codec support?

I'm looking into buying a sound bar, and I'm curious how important it is to get one with support for HD codecs. Specifically, I am considering getting either the Sony HT-CT150 or HT-CT550. In the Amazon description it says the 550 supports Dolby TrueHD and dts-HD, which the 150 does not. This seems like it might be a problem; for example, some reviews I've read said that streamed Roku movies have noticeably worse sound on the 150 than the 550 due to the better codec support in the 550. However, from my (admittedly basic) understanding of these things, since no bar is actually producing 5.1 sound, won't any HD audio streams automatically be downgraded to a lower quality equivalent? Is it worth it to spend more money to get more codec support?

Thanks, BobL. I will be playing a lot of Blu-rays, and plan to connect everything via HDMI, so I will definitely be using sources capable of outputting TrueHD and dts-HD.

Yeah, wouldn't be using optical or coax, just HDMI. So it sounds like this is pretty much an unnecessary feature.

For reference, here is what brought this issue to my attention:
"There's a major shortcoming with the CT150, and that is lack of support for "Dolby Digital Plus", "Dolby True HD" and "DTS HD". This means that you cannot play surround sound on the Netflix app w Roku. Other devices (e.g. PS3) may do downcoding, but Roku does not. This means Netflix + Roku + CT150 = stereo sound--which is worthless. This is pretty critical if you consume most of your video through the Roku as I do. See the owners manual page 36 for a complete list of supported streaming encodings. I was rather disappointed when I read this. i.e. don't buy this unit if you use Roku + Netflix."
http://www.amazon.com/review/R38WC3F24IT1V6/ref=cm_cr_pr_perm/?ie=UTF8&ASIN=B003C1AO2I&linkCode=&nodeID=&tag=