I've used both the Panasonic SD-253 and the Breadman Ultimate. There are pros and cons for both of them:
The Panasonic's bread-bucket is a seriously chunky piece of kit while the Breadman's is much lighter, although perfectly acceptable. The Panasonic's non-stick coating seems a little less robust although the odd scratch doesn't make any difference. The Breadman's bucket is also tightly retained by two spring catches while the Panasonic's can rotate a bit too much for my liking.
The mixing on the Breadman isn't as good as on the Panasonic, in that it is easier to get pockets of dry ingredients in the corners so it is a good idea to ensure you have a wooden or plastic spatula around to scrape round if necessary.
The Breadman is much more convenient to use - the window is very useful, as are the Pause control, the one-hour power-loss memory and the user-definable programs. I haven't ever got round to using the Jam facility on the Breadman but I will at some stage.
In my experience, the results with the Breadman are somewhat better but that may just be subjective!
All in all, I prefer the Breadman Ultimate to the Panasonic (despite what Which? has to say about it) - it's more versatile, easier to use and gives me more control.
The killer is that the Breadman is also cheaper - Robert Dyass are selling them on ebay at =A355 delivered (Salton is Russell-Hobbs over here). I assume that the arrival of the new Breadman model is causing the discounting of the current (to us) model but I also hear that the new "whizz-bang" model isn't much of a real improvement.
As for the "lack" of a USB port, I can't honestly imagine why I would want to bother with such a thing (and I'm a Computer Consultant and the Ultimate Gadget Man according to my friends).