Help with sequential podcast playback across multiple feeds

Hi all, my fourth-generation "gum-stick" (no buttons) iPod shuffle has been great for podcasts (that's all I use it for) but it is starting to play up, and I need to consider a replacement. The particular functionality and navigation for this model works fine for me, but I am worried that current model iPods (shuffle or others) have different behaviour, and I am looking for some recommendations that will suit the way I like to listen to podcasts.

A bit of background: My iTunes library has thousands of podcast episodes (mainly spoken word) in hundreds of different podcast feeds. I still add new podcasts to the list fairly regularly. I use the iTunes "automatically add" feature to add the one least recent unplayed episode from each selected podcast to my Shuffle.Then each time I sync the Shuffle, the played episodes are replaced with new, unplayed ones. While I'm using the iPod, I am doing other activities (exercising, gardening, etc.) and I want to have a continuous feed of audio that I don't need to interact with, other than start/stop and volume. I don't want to have to stop what I'm doing after every podcast episode and select another from a list.

The 4th-gen Shuffle has a voice-over menu option for "podcasts" and if I go to that, it will sequentially play me all the podcast episodes (from all the different feeds) on the device, in alphabetical order of feed name. I usually sync some 24 hours worth of podcasts each time, and I don't have to manually manage a playlist in iTunes. Once loaded, I don't have to think about anything, and just keep listening until I get back to "a" again. I have read that the new Shuffle treats each podcast feed as a playlist, and this means it would be way too frustrating for me to cycle through the menu at the end of each episode, especially when some feeds are short radio excerpts of less than a minute's duration.

On my iPhone, by the way, I can't seem to find a way to play podcasts continuously like I describe above, and the only way to get continuous playback would be to manage some sort of smart playlist in iTunes - and this would work on any i-device that supports playlists, but there are two problems. Firstly, there is no way to build a smart playlist that selects podcast episodes based on release date - the closest option is "date added", and when you have downloaded all the back-episodes of a podcast series in one go, the "date added" is almost always meaningless. The bigger problem, though, is that with the size of my podcast collection, building and maintaining that playlist for one episode of each podcast would be a LOT of work. (I'm not exaggerating. It's really fiddly building a smart playlist based on podcast names, that selects only one episode from each of a hundred or more individual podcast feeds. Unless someone has a smart solution???)

Anyway, now that I've made that clear, my main question is whether anyone can confirm from their own experience that any of the current iPod models (shuffle, nano, even classic) will support the kind of podcast playback I'm used to. Failing that, I'd be happy for any tips I'm missing on how to produce a playlist for the purpose of filling my iPod without losing all my remaining hair in the process. Option three is, I suppose, looking for a functional second-hand fourth generation shuffle! ;-)