SciAmMed remains more encyclopedic, at least at present. Having access to visual information that is presentable without scanning or using film allows much easier preparation, and allows very rapid development of talks. SciAmMed cannot do this, in fact, it cannot even print out tables. The publishers of UpToDate allow and assume that you will make a copy on your office machine and also one on your home machine or powerbook, without any hassle. The other big advantage of this policy is that with increasingly cheap, big hard drives, you can copy UpToDate to your hard drive for extremely fast access to data- can't do this with SciAmMed.
Technical support is excellent.
I think SciAmMed is getting a little long in the tooth, and would recommend that anyone, especially anyone interested in renal medicine, check out UpToDate.