Well, no, I was commenting on how systems can fail for both standing and seating. I'll continue to draw a distinction between the safety of both until a convincing argument is put forward. I fail to see one hiding here. "And the merit of safe standing in terms of safety has to be apparent to the satisfaction of all at the very start of that debate." <--- that's not happened. So don't be surprised if the distinction continues to be made until it does. FSF have tried, but I was unconvinced because I've stood on the real thing - and I know some of the FSF's arguments are misleading to put it mildly. If you want to wander within the terracing, away from your allocated spot, you can. With the check system, it's fairly common for stewards to not have time to check which block you're meant to be in - there's a cultural difference which plays a big role here as to why it doesn't happen more regularly. Hell, German hooligans used to be the ones sat down; it's a different football culture. I also know you're incorrect about the bunching, though it's mitigated to a degree in Germany because German safe standing areas are sold under capacity to ensure crowd safety. But let's transplant it straight into British football stadia? Better start convincing people with some well thought out arguments beyond 'it works in Germany'. Just my twopennyhalfpennyworth.
This
http://www.wsc.co.uk/the-archive/906-Grounds/549-standing-in-the-bundesliga plucked more at less at random from a google search is no academic or authoritative study but it does headline the issues in practice of standing in Germany.
However, the evaluation of the safety of safe standing in the UK has to be looked at through the eyes of UK regulation of not only the physical system of seats and barrier but also the system of control and stewarding. As you say, it's not good enough to say it works in Germany and leave it at that.
But if you look at safe standing and measure it against UK regulation it is safer than 'UK standing' by any standard within those regulations - principally because the barriers are closer together. Every other row. To an old kopite, it’s tame and many would be disappointed. So be it.
UK standing is a much improved version of the old-style terraces. It is nonetheless considered safe for every sport in the country bar one (football) and only in the top two divisions.
Safe standing is completely different, as you aware. Having been in both (I assume), you would have to agree that the standard of safety goes well beyond UK standing.
If you have experienced enough room to move around in safe standing in Germany you have experienced safe standing at a safer level. With a barrier every two rows, it's not like pin-balling about on a half-empty kop ever was.
The tickets sales and names and addresses (and in the case of safe standing, ‘standing on blobs of paint’ as it were - they don’t really) are about controlling behaviour. That has a link to safety but it is not about safety per se.
Poor behaviour can happen anywhere. Throwing coins and letting off flares can happen as much standing in the Südtribüne as it can sitting at Old Trafford.
As the article mentions, proper stewarding is essential. I have never once not had my ticket checked on going up the steps into the Kop. In that respect maybe UK stewards do better than German stewards. But despite UK regulations our stewards clearly struggle to keep people sitting down. People want to stand and seemingly nothing will stop them. Much better to provide for that safely (whether 'seated' or not) than continue the struggle in vain.
Safe standing as applicable in the UK would be as safe if not safer than seating in the UK. Not because ‘it works in Germany’ but because it exceeds all the safety precautions. It has all the safety precautions that UK seating has and more.
Even the police, who are quite rightly now in an acutely sensitive position on the matter, agree that safe standing if not 'normal' standing (the distinction between safe standing and standing is not made) is safe. The issue for them is controlling Hooliganism, which is about safety per se and not about the causes if Hillsborough, which is about where I came in...
http://www.guardian.co.uk/football/2012/dec/11/police-consider-terraces-standing