I'm with Robert on this. You need to lose 2% of bodyweight in dehydration to register a measurable impact on performance. That's a lot of liquid, and there is no way you will sweat that in 1 hour, no matter how hot/hard you ride.
I take electrolytes with me on rides over an hour, though it often comes back undrunk, and some food on rides over 2 hours, though it often comes back with me uneaten.
You must be pretty unique at 10 mile TTs with water. I would resent the time out of the tuck to drink.
Not to mention the aerodynamic disadvantage of carrying a bottle along 
Yes I'm another in the 'there's a lot of hype' camp.
I first started cycling seriously in Western Australia and have lived and ridden (and raced) in W.A., Queensland, Switzerland (Alps), Italy etc. so I think it's fair to say I'm pretty use to exercising for long periods in fairly extreme conditions. Consequently I know pretty well how much liquid I need under any given conditions (weather and terrain).
And I find people get really paranoid about drinking and about energy drinks especially. It's like a small drop in performance will do for them - and let's admit, most of us are not going to be performing anywhere near 100% so if you're performing at 60% instead of 58% in a sportive, does it matter? And that's assuming you've lost that 1.5 - 2 litres of liquid. Remember also weight loss at the end of a ride doesn't simply equate to dehydration - each gramme of stored glycogen is associated with 4 grammes of water. So 2000 kcals (usually considered the max stored) is 500g CHO and 2000g water which you will also sweat out or pee out. So if you have a hard ride which depletes stored glycogen you may think you've come back 2kg dehydrated but no amount of drinking will sort it until your body rebuilds the glycogen stores, so we're not talking about plasma loss which is what causes the loss of performance (although there'll be a much bigger drop of performance if you run out of CHO).
I think it's likely that most people get into the habit of using (energy) drinks as a psychological crutch. I've posted on here before about drinking only 3 or 4 litres of liquid (mainly water) on 200km and 300km audaxes (admittedly under cool Scottish conditions) and not feeling completely done at the end - or in fact being more than slightly (< 1kg) dehydrated. Now it could be that I'm a human camel
or more likely that experience allows me to gauge what's required and have the confidence to know what works for me.
The thing about psychological crutches is that when they're not there, you fall over
so I'd avoid building a dependency:
- Ride as often as you can with just water (I always take a bottle as there's nothing like half swallowing a fly and not having a drink to hand to wash it down
) and drink just what you feel to need - not by rote e.g. 'you must drink a bottle every hour or you'll bonk/die of dehydration'.
- Learn to judge whether you're drinking enough by what you feel like at the end of the ride and the next day.
- Learn to distinguish
muscle fatigue from dehydration/lack of energy - many people are sufficiently unfit that tiredness means just that - their legs are tired and not sufficiently well trained for the load - it's nothing to do with lack of energy or fluids which is why necking gels won't do anything (hence the cry 'gels are useless, they never work for me' - well, they don't work instead of training
).
