For work-related purposes I'd still have to recommend a laptop for an SM. While tablets are an excellent supplement to a laptop, they're not quite robust enough to make a laptop obsolete - especially for the duties of anyone on an SM team. If your primary reason for getting a tablet was reading and referencing documents or media on the go and writing some basic emails, then yes - a tablet would cover thoses tasks effortlessly. However, SMs are almost always the document
creators. How many reports, spreadsheets, word documents, etc.. are created or modified on a daily basis? For me a tablet would just not cover that (especially as anally retentive as we are

).
But - at the end of the day, "how long is a piece of string?" There are a million answers and this will ultimately boil down to your personal preference. That said, hope the opinions of all here are helpful in making your decision!