Many here followed Walter Colebatch's Sibirsky rides for years. He developed those Magadan bags on his rides and has done a great promo job selling them.
I think he now has a lot of competition from firms like Mosko Moto, Kriega, Giant Loop and others. Adventure gear is now big business. $$$$
I would not buy any of the above brands ... due mostly to price.
Both Adv spec Magadan and MoskoMoto bags cost between $700 and $900 for the set, IIRC. (may have gone up in price by now?) If I were planning to spend the next 20 years living off my bike (and out of those bags) traveling (I wish!) then perhaps I could justify spending upwards of the 1000 USD on panniers.
But my Nelson-Rigg panniers only need last a couple years ... and based on prior experience with 3 previous sets, I'd say they'll make it fine with years to spare. My last ones I just sold off were still perfect after 5 years and 4 major trips.
My new (not yet received them) Nelson-Rigg 3050 Sierra Adventure dry bags are now on sale for $156 USD. It they turn out to be total crap ... it's not a huge loss and I'm positive I can re-sell them for $100 at least. But I'm confident they will work OK.
I know Nelson-Rigg gear is made in China ... and I would BET all the other expensive brands are too.
Differences? There probably are some, but it's mostly about "prestige branding" and more money into the pockets of the owners of those trendy companies who run HUGE mark-ups.
But it's good to see innovation in this segment, but not sure all these so called "new" designs are in any way ground breaking, and some features may have them "going backwards" Just IMHO.
But please, "carry on" to those who want to spend that much money on simple canvas bags made in China at $25 per set. MASSIVE mark ups and huge profits is what I see.
Some low cost bags are real crap, some are adequate ... like those Scottish ones mentioned a page back. (pics, web site would be nice) Bike panniers are not rocket science ... those Mosko's and Magadan's are overpriced.