Oh dear BigLouis, has Prague joined Barcelona as being sadly famous for street crime??
That's a shame. We went to Prague before the Iron Curtain collapsed, so an odd experience, being eyed with suspicion by Police, and as potentials to get some foreign currency by desperate locals! And it was a real eye-opener, to see what the 'glories' of Communism really meant, just about naff-all in the shops, and meat at a premium for our meals!
Oh, and on the sad note of Communism, on our tours of Prague (on buses!) and later on Bratislava, we saw several parties from E Germany (presumably the chosen lucky few of the party faithful). Despite the shortcomings of basic life for the Czechs, they regarded themselves as far luckier and better off than the Germans, so we could only guess how horrible life was for THEM!
As for the perils of a walking tour, well, that's the price of going in groups, isn't it? We've had coach tours when some selfish nitwit (or a couple) has been late back so upsets the schedule for the day or half-day, lots of THEM about!
We'd be more likely to set off with a guide-book or some notes and visit places on our own, though IsNibs has been waiting months for a hernia op (postponed once, at about 18 hours lack-of notice!), so we can't walk for miles anyway.