I'm also eyeing the new TiVo Premiere and TiVo Premiere XL models introduced last night, which have much faster processors and much bigger hard drives at the same price points as the old models. They also get the new TiVo user interface, which we've gotten to see in the "beta" version of TiVo Search that's been available on TiVo Series3 and TiVo HD models but that feels awfully slow. Thus the faster processors. The consensus is that the new UI will not filter down to the Series3 boxes, for just that reason -- it won't be a good user experience if it's that slow, no matter how pretty it is.
As with the old TiVo HD and TiVo HD XL models, the Premiere XL model adds a bigger hard drive and THX certification, and the fancier backlit programmable remote, but that's about all you get for your extra dough. Buying the low-end model with an expanded hard drive from Weaknees is likely to be a better bargain, once they make those available.
Interestingly, the new UI is based on Adobe Flash, which I hadn't realized. It seems like as good an engine for that sort of thing on the TiVo platform as any, but as Apple will tell you if you grumble about the lack of Flash on the iPhone, it's processor-hungry. That does explain why the Search beta feels so sluggish.
There's really no need for me to buy one of the new models anytime soon, because my TiVo HDs in the TV room and the bedroom are just fine and, with their external drives, have plenty of recording space. What I and others are hoping is that TiVo will eventually incorporate the "tuning adapter" functionality from the Cisco or other set-top boxes that resolve the Switched Digital Video issue into the TiVo box itself, so you don't need to have that external box, which I dubbed the "cable de-assifier."
One nice feature of the TiVo Premiere (or Series4) line is the availability of the optional keyboard remote. It looks a lot like the TiVo peanut remote, but you can slide out a QWERTY keyboard from the bottom. Such an idea is getting increasingly useful, as more and more things beyond searching for the TV show you want, like looking for YouTube or Amazon videos, typing in video podcast URLs, and so forth, demand lots of text entry that gets annoying when you have to click around to each letter on the on-screen "keyboard." There are hacks that let you do that from your laptop, but something official is getting more and more important. This device works via Bluetooth, so you won't be able to buy one for your older TiVo models.
For anyone who doesn't already have a TiVo that meets their needs, these do look great, but I don't think most people who have the previous generation of HD boxes will be jumping to upgrade. We've already got all of the features.