For commuting, you'll get very little benefit from moving to either Octalink / ISIS or external bottom bracket setups. When I first fitted ISIS (oversized bottom bracket on a splined axle) to my MTB, there was a noticeable difference in climbing... so much so that I actually got off my bike to make sure something wasn't wrong with my clipless shoes, it was that much stiffer!
But really, the reason for the square taper design being replaced came from the upper echelon of the sport where people demanded more direct power transfer (less flex) when they stomped on the pedals, and greater strength to compensate for hard landings as jumps got bigger and bigger. However, from an every day users point of view, the splined interfaces came about as they were THAT MUCH HARDER to stuff up! There's a stop on the axle, so that users can't easily over tighten them and ruin the press fit. There are downsides to both technology, but the interface you currently have is now only found in the very entry level bikes on the market.
got a second-hand one from a local shop (they had stuff not listed on the website). $25 all up. it seems a little wonky (like my foot points inward at some part in the cycle, not sure why, maybe the arm is a little bent? or my pedal is weird? or the bracket _is_ a little fcuked? or maybe I'm just not used to it yet...s'what I'm counting on), but it's an improvement on a totally rounded wobbly crank.