I use a 50 foot hdmi from pc to projector with no quality issues, video only, but I would recommend media pc of some kind if you have to carry video and audio that far, everything else is a constant codec headache or streaming bandwidth issue. For me it should be full pc and not separate device for media. You will be glad you did it.depending on exactly what you are streaming I wouldn't necessarily agree. Most media streamers can now play pretty much every file type. With PCs you can have all sorts of problems playing around with codecs, video drivers audio drivers, OS upgrades, the OS upgrading your video drivers, etc.

A PC is much more functional but it is also much higher maintenance.

I use 6 SageTV extenders in my house connected to my SageTV server. They work flawlessly for playback of all types of media files. The only downside is that they can't do web browsing and they are not ideal for online content like Netflix.

IMHO, using/buying long expensive HDMI cable is only worthwhile when installed in-wall to a projector, etc where it is not readily reachable to pair with other devices. For regular HDTVs in an entertainment area, there are just too many cheaper/more flexible alternatives.

RG6 + Cat5/6 cables is the bare minimum these days connecting each room/media area to various computers/storages/servers. There isn't anything network cable + RG6 couldn't do these days.

depending on exactly what you are streaming I wouldn't necessarily agree. Most media streamers can now play pretty much every file type. With PCs you can have all sorts of problems playing around with codecs, video drivers audio drivers, OS upgrades, the OS upgrading your video drivers, etc.

A PC is much more functional but it is also much higher maintenance.

I use 6 SageTV extenders in my house connected to my SageTV server. They work flawlessly for playback of all types of media files. The only downside is that they can't do web browsing and they are not ideal for online content like Netflix.
Ditto that.
I haven't used HTPC much for the past 1.5 years. It's either WDTV Live or Box Office, >>90% of the time. However, PCs still unbeatable for online usage.

The 2 HTPCs that still get actions are the kitchen PC and the HTPC connected to the projector. The main reason I still use HTPCs there is because the HDTV in the kitchen has no ATSC tuner; neither does the projector of course.

HTPC in this case is the best all-in-one solution for media playback + OTA HD.

So, back to the OP's question, if you're going to spend big bucks on HDMI cable (like a couple of hundred bucks), you might as well get a basic dual-core PC to the TV.

The SageTV extenders look to be pretty limited too with only S-Video output so you're restricted to 480i, and the SageTV Server I assume runs on some type of OS and can be regularly updated so it's a bit different then a media device where you are at the mercy of a vendor firmware update. I'm really talking about media devices in comparison here, and not to say there are some that don't work well today I'm just saying they are less versatile at playing media then an HTPC.

At some point you will run across a new media file type you want to play, or some oddball audio codec someone added into an MKV container or a video file that doesn't quite adhere to specs and devices will cause you grief whereas an HTPC you can simply download and install what you need to play the file and off you go. In the end whatever works for your situation but these are my thoughts on devices.

The SageTV extenders have HDMI and component output so there is nonissue there. You can use them in standalone mode or in extender mode - extender mode gives you the exact same UI as the SageTV app on your PC. This allows you to stream live TV, including HD, and to fully control your PVR/media system. I have six of these in my house.

While it is possible you may come across a file type that won't play, I haven't seen that with these devices. They are less flexible but they may be more than good enough and there are other advantages: totally silent, low power consumption, cheap ($150), low maintenance, etc. If you just want media in one or two locations than a PC is fine, but if you want many end points then these make sense.