I've used ortlieb classic rollers for almost 20,000 km now and I recently swapped my front rollers with rear bike packer plus ones. The bad thing is that I now have so much capacity that I tend to carry so much crap!. Here is a copy of what I wrote about the panniers in another thread:

I've been using rollers for some five years now and I decided to buy bike packers plus to replace my small front rollers. I've just started a trip with the packers and I think I've used them enough now to make a good comparison... Here is what I like/dislike of each design:

ROLLERS
What I Like:

• sturdy fabric, it is more like thick PVC, practically indestructible.
• can be filled to the very top giving almost another 50% capacity (but without closing it)
• when closed you can use the outer strap to fix yet some other thing on top of it, this is handy to attach last minute stuff without having to open the bag

What I Dislike:

• they're heavier because of the pvc construction.
• they have the older hooking mechanism which doesn't work as well as the new one on the packers. Actually, I have to pass a rope trough one of my older rollers because when heavily loaded it tends to unhook from the rack when I pass over a bump at high speed.
• they aren't very comfortable to carry by hand because the handle is on the very edge and the bag weight is always off center.
• really hard to close them without both hands and your full attention (having to get off the bike)

BIKE PACKERS PLUS
What I like

• Theyr'e light and compress better when empty because a much thiner plastic coated fabric.
• The new hooking mechanism which can be adjusted without using the hex wrench.
• They have a centered handle allowing for a comfortable carrying by hand
• They look really nice when full and closed
• The internal mesh bags are handy and don't get in the way if you don't have to use them
• I haven't used the external bags yet but they'll be handy whenever I need them

What I dislike:

• The fabric is way more fragile than the rollers's.. I already tore a small hole in one of them when it rubbed against the floor.
• The closing mechanism doesn't allow you to fill them as much as the roller's