You've got to love tools and accessories that just get out of the way and let you get on with the job at hand. Shooting the first full dress rehearsal of a live production usually throws up a few challenges in terms of timing, location, stressed performers & egos etc, and the last thing you need to be worrying about as a photographer is equipment. There is precious little time between costume and set changes on a live production run of a show to reset or make changes - you are looking at a 2-3 shot grab of a character and you are done. Needless to say, lighting is critical. 

3 things I've been very eager to try together this year is the new Canon 5DSR, the Sigma 50mm Art 1.4 & Profoto's B1 - I recently took all of them to Prague to see how they would perform individually and together. The Sigma Art Primes on the 5DSR can only be described as other worldly when paired with Profoto's B1 - and while the Canon 5DSR does present some unique challenges in real world use, the files it produces are truly sublime.