Interesting comments about your diving experiences in South Africa. I'd be curious to know where the diving was done.
The surf launches that we do here can be quite daunting but a boat actually capsizing is a very rare occurrence.
At least that's not really something you'd need to be very concerned with if you're planning on diving Tofo. The launch site there is inside a large bay and there is virtually no waves in the immediate area of the launch. The launches in central Mozambique (Inhambane, Barra, Pomene, Guinjata etc.) are generally much easier than southern Moz (Ponta do Ouro, Ponta Malongange etc.) and the northern Natal coast of South Africa (Sodwana, Aliwal Shoal etc). Aliwal Shoal can be particularly hectic.
As for the diving conditions, I think again you must have been rather unfortunate. Of course the ocean has a mind of its own but along this stretch of coast very poor viz is certainly the exception rather than the rule and if there was very little to look at I'm tempted to think that you weren't dropped on a reef. The reef system here is very rich in life, ranging from tiny nudibranchs to Whale Sharks.
I hate to say it but the police in Mozambique is corrupt, there's just no other way to put it. It's really sad as the tourism opportunities there are brilliant. I'd hate to hurt their tourism industry by saying things like this but I do think they need to sort that **** out and if they don't they deserve losing out on tourism revenue.
Having said that, its not so bad that I wouldn't go there again. If I had the opportunity, I'd go there tomorrow (especially Tofo). The only place where you're likely to have a run in with the police is while you're driving to or from Inhambane or wherever you're going. As long as you do nothing wrong you're also very unlikely to have problems but if you break the speed limit or don't wear your seat belt and you get pulled over you will not get off without paying a "fine" on the spot. By "fine" of course I mean "bribe".
Like I say though, if you do everything right (and by that I mean slow down to 40 before you even get to the sign that says 40) you really have little to worry about. As corrupt as the police are, I wouldn't say your safety is at risk. Once you're at Tofo you won't see or hear from the police until you take the road back to South Africa again. If you'll be flying in to Inhambane you also won't have any of those worries.