I do notice a difference, though I don't think about it past about 1-day. Ask me to and I'll still feel the difference.

I prefer longer cranks, honestly, though I spin better with shorter ones. Thing is, terrain undulates, and I'm constantly having to up my input to stay at speed...long cranks give me the leverage and allow me to power-through those undulations.

However, I don't ever buy cranks based on length unless I'm trying to use the length to help with bike-fit. For instance, a bike with a shorter headtube means I either have to spacer up the steer tube or get longer cranks to lower my carcass...or both. It can be the make or break for a bike with a good TT but an otherwise funky fit.