Hey there @HankG!
I just got my REI Co-op Link Handlebar Roll delivered and I am eager to try it out. I'll be sure to let you know how it works. By first estimation it looks really solid and I'm excited to use it.
On my first bikepacking trip I used a 'self-invented' (and I mean that in the loosest of terms) set up on my handlebars. I have a Salsa Anything Cradle, which I really appreciate for a couple of reasons: first, it is rigid and stable, meaning there is less bouncing and jostling of gear around my handlebars, and second, because it sticks out from the handlebars, it creates a sort of 'platform' where I was able to strap my sleeping pad, bear spray, and dog leash on top. One drawback to this system is it's weight (not important to me, but to some) and the fact that by pushing your gear out in front of your handlebars it could affect steering and your ability to see obstacles on the trail. I found neither of these cases to be issues for me, however, I don't go very fast either.
Inside the Salsa Cradle, I used a double ended compression sack (sewed by a friend) and half of a Thermarest Z-lite sleeping pad wrapped around it to give it a bit of rigidity. I have my Thermarest cut in half because I use one half as extra insulation on the ground under my inflatable sleeping pad and my doggo gets the other half to help keep her warmer and more comfortable. You'll also notice my bear bell attached to the whole set up to give the impression that Santa is coming down the trail with all the bouncing and shaking of the suspension on the bike.
All in all this kit did the trick, however, it was a bit challenging to get strapped on correctly and dialed in. That's why I upgraded to the Link Handlebar Roll. I will likely continue to use that in conjunction with the Salsa Anything Cradle as I like having some more storage on the handlebars. I'd be happy to use the just the roll for a while and let you know how I like it.
In terms of the Ortlieb 15L Handlebar pack, I've done trips with folks who used it and enjoyed it. Having the ability to release air when trying to compress it is pretty handy. The elastic cords allow you to add some items, similarly to the daisy chain loops on the Revelate Designs Sweetroll Handlebar Bag. As all three of those seem to have similar systems for attaching them to your handlebars, it is likely that any issues you may have with cable routing would be the same (another advantage of the Salsa Anything Cradle).
Hopefully this helps, I'll keep you posted once I've used the Link Handlebar Roll!