I think the Tungsten E is excellent value and is almost certainly enough for your needs. Having said that I've just ordered a T2, because it's already being heavily discounted (I'm in the UK- the T2 has just dropped to ?199, compared to ?140-150 for the E where available. The T2 was ?329 when it first came out over here!) Although I'm not sure that I'll use Bluetooth I might, so it'll be nice to have that option. I also figure that the cradle, voice memo and brightness/backlight adjustable display were worth the extra. I'm a Radiologist btw, and there's lots a radiology software available which I might have to get; I presume there are texts for other specialties too.
For medical professionals, any PDA with expansion card support and at least 16 MB RAM should work fine. You can keep your references on the card and the apps either on the card or in RAM. You'll want large cards--256MB minimum--as most references run upwards of 5-6 MB, with some exceeding 10 MB. They add up quickly, as do other apps you put on the card. That points you towards Palms with SD cards or OS 5 Sonys that support Memory Stick Pro format. The latter are significantly more expensive. The Tungsten E would be a good choice, as would the Sony TJ35. The latter requires the more expensive MS Pro cards, though. CPU speed is less important that card access speeds.