I use Ortlieb Sport rollers as my main panniers, they're only 30ltr but I can add 10ltr stuff sacks to the top of each for very little additional weight (Though the sacks are not 100% waterproof)
A photo to illustrate. The stuff sacks don't stop me using the platform of the rack for stuff the same width as it. Another advantage is the extra volume adds height rather than width, it can be an advantage, particularly off road. The stuff sacks would make it awkward to get stuff in and out of the panniers on route, though with a saddlebag and barbag there shouldn't be any need for me to do that.
(https://live.staticflickr.com/7369/8720563425_25cf51c388_z.jpg) (https://flic.kr/p/ehBaFP)Journey end (https://flic.kr/p/ehBaFP) by Paul (https://www.flickr.com/photos/phbike/), on Flickr
NB: Obviously I don't tour anywhere that requires the same amount of luggage as mickeg
I bought my Front Rollers about 15 years ago before the name change. You bought your Sport Rollers about 25 years ago after the name change.
One of us must have a time machine.
The first trip I used mine was in fall 2010, which also happened to be my first trip with my Sherpa.
If I had a time machine I'd hope to put it to better use.... more likely to be a fuzzy memory. it was these blue one I bought 25 years ago (Actually 27) they were sold as Front.
(https://live.staticflickr.com/4619/25853524958_b2fa0cccdc_z.jpg) (https://flic.kr/p/FoA5fj)loaded raven (https://flic.kr/p/FoA5fj) by Paul (https://www.flickr.com/photos/phbike/), on Flickr
By the time I bought the grey ones, somewhere around 2013, some places were calling them Sport, at least in Germany where mine came from. Maybe there was some overlap in the naming (Intentional or not), maybe someone remembers when the lighter Plus type were introduced (I'm pretty sure these were never called Front) I thought the name changed at the same time as the branding on the front, though I could be wrong. I wouldn't be surprised if some retailers still refer to them as Front, it's just a name, the main point is it ought to have been established by now that they're suitable for use front or back.