I used Alu panniers RTW last year and they were great until I crashed in Mongolia and ripped a lock out, meaning I had to strap the box back on with a ratchet strap, thereby losing the convenience and relative security. But I'd rather have that than a bag ripped open and all my stuff strewn about the place. I'd like to think they protected other parts of the bike from damage on several occasions when I dropped it, but that's also just speculation.

They were very convenient for packing, swallowed a lot of stuff, and gave me somewhere to put all my stickers including my world map with my route marked on it, which was a great conversation starter. It made me less nervous about having stuff pinched, too.

They also were very useful as a table, a chair, and a bike stand. And not much more expensive than quality, waterproof, secure, robust soft bags.

On the other hand....

Security wasn't as much of a problem as I'd feared, and I was either near the bike or took everything off anyway.

I'm not sure what I would leave out, but having that space available probably meant I took too much stuff. I suspect I wouldn't have crashed anyway if the front hadn't been so light, and I certainly wouldn't have had so much drama on the trans-siberian with a broken frame and snapped pannier rails if I hadn't been carrying all that weight.

But...

I still can't decide what I'll use on the next trip.

I'm thinking about something halfway - maybe smaller, lighter boxes, perhaps even plastic ones. And less stuff (still struggle with that - all the stuff I never used on the last trip, I still tell myself that if I don't take it I'll need it, same goes for the stuff I ditched at the side of the road in Siberia...)

Perhaps a small lockable topbox for security/convenience/stickers, though I'd be equally concerned about weight up high and out back like that.

And definitely always wear proper boots!

Makes me cringe when I see someone riding in flip-flops or walking boots.