I prefer the Classic Back and Front rollers. My wife, a very savvy and experienced bike tourist, prefers the Packer Plus.
I think it is more personal preference rather than one having a distinct advantage over the other. I don't think you can go wrong with either set.
The fabric (red)a on my wife's Packer Plus front panniers have faded from UV exposure. She has been using them for commuting as well as tours for the last 7 years so a little fading is probably OK. Her yellow Packer Plus rear panniers are still bright and shiny , even after 6,000 miles of touring. However, they are only 3 years old.
She also carries the cable, lock and sunscreen in the outside pockets which is really handy.
I like the rollers because I feel the fabric is a little easier to clean, and I believe it is more durable (no proof just perception). I was also a little more frugal and weight conscious when I purchased mine. I also keep the items that I feel I'll need during the day in one of te front panniers, which are easy to access. I did not think the outside pocket would be an advantage. That assumption is mostly true.
My front pannier after a high speed encounter with a high curb. While it looks bad, it is really just a "flesh wound", and is still waterproof.
My wife seldom uses both front and rear panniers. Depending on the tour she will use the Packer Plus front pannier in the rear along with her rack pack as shown in this photo. If she wants to carry more gear she uses a "real" rear pannier.