I ended up getting PlayOn so that I could use Amazon Prime and NetFlix with my HTPCs so I added PlayLater, too. I also picked up Audials Moviebox when it went on sale at Amazon for $11.
PlayLater is much easier to use. It is pretty easy to setup and the queuing feature means you can set up a whole bunch of programs and just leave it. It most certainly will do HD. If you are having trouble with it then you are most likely having HDCP issues with your PC and the content provider is limiting you. Most of all, it just works. I have recorded a few hundred things with it and it has only dropped 4 or 5.
Unfortunately, it is far from perfect. Even at the highest settings, MediaMall has limited the recordings to 1280x720 and everything is 29.97fps, regardless of the source. There is noticeable judder on anything that pans. Movement in live action feels a little unnatural and disconnected. I recorded the first season of Friends from NetFlix and then just deleted it. It is definitely HD. When playback is paused, the picture is sharp on my 50" and it looks good but the motion is just so weird that I have a hard time watching it.
My family isn't as picky and truth be told, simple animation looks really good. I pulled down all of the My Little Pony episodes (4 seasons) from NetFlix using PlayLater and everyone is pretty thrilled with it. There is still a little bit of judder but generally, the motion looks pretty good. Same for Barbie: Life In the Dreamhouse and the Ever After High episodes. I use PlayLater with reckless abandon when it comes to animation for my kids. I don't use it for anything live action that deserves any kind of quality. I started a thread about this on the PlayLater forum and there was a lot of activity on it a couple of weeks ago. I have found the PlayOn/PlayLater/MediaMall staff to be very responsive to issues and their support is awesome and they actively monitor the forums and participate in the conversations. In fact, the latest update to PlayLater is now using L3.1 h264 profile instead of L3.0 and it appears that the conversation in the forum was a huge factor in that. I haven't had a chance to do any serious recording since the upgrade so I am not sure how this has affected some of PlayLater's shortcomings.
I use Audials Moviebox when PlayLater isn't acceptable. There is no queuing feature so you have to start each recording manually. The range of settings is huge and it is easy to pick an h264 setting that is to taxing for my FX-6100 CPU. In fact, I have found that the most reliable way to get HQ recordings that don't have dropped frames is to record programming using WMV and then transcode the file to h264 using Handbrake. I'm sure there is a more conservative h264 setting that would fit my needs but I haven't been able to spend the time to figure out what that is. If Audials offered the queuing feature of PlayLater I would dump PlayLater completely.
In a nutshell, PlayLater has been good enough for basic HD recording but was really pretty lousy if you are conscious of any kind of quality. However, the L3.1 upgrade to the video profile might have increased the quality and it is definitely something I need to check out very soon.
***Downloaded a couple of music videos from YouTube using PlayLater and the quality is noticeably better with the change to L3.1. Crisper, cleaner with less artifacting and much much less blocking***