I know that I'm a little late here, but a few comments:
Scientists have been successfully sued for stating that homeopathy is "bogus". The fact that his statement is demonstrably true didn't help at all
As far as I am aware, there has been no English defamation case involving homoeopathy, and a quick search of the case law databases don't turn up anything. I think the case you are referring to was the one between the British Chiropractic Association and Simon Singh. The key phrase Singh used was that the BCA "happily promotes bogus treatments." The lower court (helpfully called the High Court) said this was a statement of fact, that the BCA knew what they were doing was bogus. The Court of Appeal said instead that this was saying that the BCA were promoting treatment, and that Singh thought they were bogus; as this was opinion not fact (legally - obviously it is a fact scientifically) the "fair comment" (or "honest opinion" or some combination thereof) defence applied, so the BCA dropped their case.
Libel tourism is one of those things that has been grossly overblown - mainly by US politicians and lawyers, as a general "let's attack the main rival to the US legal system," I think. The article linked refers to only 2 cases; the Mahfouz v Ehrenfeld case (which I just skimmed) was one of those cases where the defendant doesn't bother to show up or contest jurisdiction (despite publicly acknowledging their awareness of the claim), so they lose.
The second case, Berezovsky v Michaels, is an older case, and might not be followed these days (interestingly, some issues of choice of law and jurisdiction have been tightened up by the EU, but defamation has fallen outside the scope of that, so is still a bit fuzzy). On the facts in that case, the Court (or House of Lords) decided that England was the most appropriate jurisdiction given that the stuff was published/circulated in the UK, damage was caused there, both B and M had strong ties to England, but didn't have connections in each others' state.
British libel laws are problematic, but not because of the substantive law, but the underlying costs; people are bullied into accepting settlements etc. because libel cases can be dragged on for years, costing hundreds of thousands of pounds (legal actions being more expensive in the UK than nearly everywhere else, except probably the US). While there are currently attempts to fix UK libel law, unfortunately the costs issue is being ignored (both in defamation and English law in genera).