We're in the same boat. Here's what I've learned so far:
- HEL doesn't have an offering for 2015 ABS, I mailed them a week ago about it and they told me they'd very much like if I sent them my lines to measure. They assume they should be pretty close to the earlier gen, so they said it'll probably cost the same, but they offered an extra bonus for being the guinea pig. I told them I'm gonna do it when it's a bit warmer outside. Once that's done, HEL will probably start selling 2015 ABS lines
- It doesn't really matter which brand of braided lines you get, they're all pretty much equivalent in performance and longevity. Maybe just avoid the Chinese stuff from aliexpress
Haven't found parts for our model in neither HEL, TRW nor EBC. Feel free to look further.
- The part numbers are different between Mk3 and Mk2, so don't buy the last-gen lines.
- Reading the service manual, there's A LOT of stuff to take off before you get to the ABS pump. Luckily, many of the same parts must be taken off for engine vacuum synchronization (which I'm also overdue), but that must be made with the engine running, not in a closed-garage, so I'm waiting for Spring until I can do both at the same time in relative warmth outdoor. Check if you also have some outstanding maintenance jobs you want to do while the bike is naked.
- You'll probably be fine with a single 500ml brake fluid bottle for both brakes. They're cheap so if you haven't done a bleed job before, you might get two bottles for the peace of mind. You'll use it next year or two anyway. Just remember that once it's been unsealed, it cannot sit for long.
- A vacuum bleeder pump is a godsend. Get one! Makes the job a breeze compared to the old squeeze-and-turn routine. I can't advise on specific brands or models, we get different stuff here. I've got a cheap, no-name tool and it works fine.
- The manual also says to replace rubber elements of the calipers and master cylinder every 4 years (or 48 000 kms, which I'm over). It's probably one of those CIY schedules, but if you decide to go with it, it makes sense to replace them along with the lines because you'll only have to bleed brake fluid once.