Flappy paddles, as I have said in an earlier post, are apparently revered in the Asian market and that is where the feature is aimed, subsequently Jazz Hybrid Sport models arrive in the UK as is. So it appears they are a marketing item rather than being something very useful for the average bloke, or sheila – please note the equality/inclusivity. If you find yourself on a race track I guess that is where they will be really useful.
As for me using them on a day to day basis, I do occasionally, because there are a few hills where I live with a 20mph limit and they are useful for getting the descent rate perfect and harvest some energy to go up the other side. It just gives me more fine adjustment over the B mode selection. They don’t get in the way and are just there if I want to use them.
As for B & D it is either Black and Decker, Bondage and Discipline, or Brake and Drive. Your choice. As for driving around in B mode I gather it will do no harm but for me I maintain it is just another control (a brake is a control) for the car and I use it selectively and don’t get obsessed with the regenerative aspect.
I say that because using D mode and slowing the car it will take a certain time/distance to slow to the point you want it to. Using B mode permanently merely shortens that slowing time/distance so you have to commence slowing later to reach the same point you want to. I see no reason that the regenerative aspect will be different, and indeed will be equal in both cases.
So the choice is long and smooth deceleration or a slightly more shorter and harder slowing down. I go for the longer slow down because I see no difference as to energy harvesting, it is better for passenger comfort, and it also stops me shortening any braking too late to err on the side of safety.