I would say to Ludwig, do not be afraid to use the rear brake, it's not all that powerful and you can test that by using it only to decelerate. It will lock up in a panic stop where the weight is all thrown forward and the rear end gets really light, and if that ever comes up, just back off (train yourself). On my '07, I could lock up the rear on rapid deceleration going too hot into a corner, trying to scrub off a bit of speed, but found I wasn't using the front. I have skidded a car tire for 50 feet, oops. Fixed that by making it a habit to use both brakes, the fronts are very effective. I've never skidded the rear if I used the fronts as well.
Meanwhile perhaps look into why the ABS isn't working.... and it may be possible to revive it. It's best to have it working for sure.
While most of the braking is done with the front, I use both. 25% of the front pads are controlled by the rear pedal if you push on it hard enough. It's like riding with your two fingers covering the front brake.... your rear pedal is at the ready for that panic stop, and you'll need all the brakes you can get.
"[The rear brake is] not all that powerful" - we agree. That's why I'm willing to keep the bike and not use the rear brake instead of laying out the cash for a newer bike with functioning ABS on both ends.
"It will lock up" - agreed, but I'll add even if it isn't a panic stop
"Look into why the ABS isn't working" - this is a known issue with Gen I bikes. If you don't actuate the ABS unit when flushing the brakes, the ABS pistons eventually gum up. Fixing generally means buying a used unit off eBay, hoping it works, and installing it. Estimates are about $1000 just to try. I bought this bike with 74K on it and found out the rear ABS didn't work after several months. I researched the fix on this board.
"25% of the front pads are controlled by the rear pedal" - maybe on your bike. But not on a Gen I, which is what I ride. On a Gen I none
of the front pads are controlled by the rear pedal. And none
of the rear pads are controlled by the front lever. That changed with Gen II in 2006.
I want all the brakes that can safely be used. I'll assume you've ridden on pavement and had the rear end lock up and come around. It creates a nasty wobble when you get off the rear brake. If you're unlucky it just plain high sides you. Reaction times are normally around 1/2 a second. That's plenty of time for the back to get further
around. And as you pointed out, as I stop more strongly with the front, the lighter the back gets, which also means the rear wheel is more likely to lock given the same brake pressure.
If you like rolling the dice on a high side, go ahead. I'll trade bikes with you. This bike catapulted me off through a 135 degree arc, where I landed head first on my head/helmet and shoulder coming down as if I'd been thrown like spear. I was going so slow the bike slid less than 15 inches on its side. I didn't slide at all, just fell like a tree on my right side. I got a[nother] concussion, broke the clavicle, and cracked several ribs. That's what can happen when the back end comes around, even when it isn't a panic stop.
For the trade, it's got an RDL, Shad with Admore, Yamaha heated grips, FZ1 mirrors, extra '03 windshield, fork brace, and significant extra wiring/electronics/lights/brackets for helping at bicycle charity rides. Oh, and some scratches, too.