I've still got the old DirecTV TiVos, SD only, but with larger hard drives installed. I'm looking into the HR-34 and HR-24 to upgrade my system.
From what I've been able to tell talking with people on the 34 and the 24, these DVRs do not have two of the features I use most on my old (and I mean OLD) TiVos--Season Passes and Wish Lists. Season passes allow you to record all shows of a certain name on a specific channel, and allow you to specify if you want first run only, or reruns too, etc, and how many total shows to keep at most. Then if the show changes times, or they broadcast an extra show on a different day, the TiVo still records it. You control priority if there are conflicts through the Season Pass Manager.
Wish Lists allow you to search on Actor, Director, Category, Keyword or Title. It will search across ALL channels. You can have it auto-record these, or use it to find specific shows to watch. For instance, if you follow Boston College hockey, you could put in a wish list with a key word of Boston College and category of hockey, and it would show you all the upcoming shows (and again, you could have it auto record these). These searches are saved once you build them.
So those are 2 things I like a lot about TiVo. I always have plenty of shows to choose from, without doing any sorting through schedules manually to find what I want to record. From what I've been able to tell, these features are not available on standard DVRs (or at least the DirecTV units). I think it has to do with the patents TiVo has, and that have been upheld in court.
I HOPE I'm wrong about this, especially the season pass part, because I really would like to get one of the DirecTV HR-34s. I'd love the 5 tuners and HD capability, but would not like to have to manually look through the guide to find what I want to record.
DIRECTV's DVRs have had series (season passes) since day one. They also have the ability to use boolean searches to do the same thing that a wishlist can do, it does take more effort, and they have had that for years as well. So I'm not sure what or where you're reading your information but it appears to be incorrect.