Originally Posted by
mattcalifornia
Here's how I look at it:
• Disk brakes won't make you faster unless you are having to descend lots of steep mountains very slowly with your current brakes or frequently have problems braking in the rain.
• Di2 won't make you any faster unless you are racing and missing shifts with your current system that are causing you to get dropped
So, unless you fit one of the 2 above exceptions, you'd just be getting a new bike because you want it. There's nothing wrong with that (so long as you can afford it), but don't expect much improvement in your riding.
Partially true
If the OP rides on less than perfect roads, wide tires will make fast riding more comfortable, and could be less fatiguing. Less fatigue can allow a rider to go faster, or longer.
Bikes with disc brakes usually all 32mm or wider tires. Most modern bikes with rim brakes are limited to 28mm or less.