I'd say gill was def the exception and not the rule when buying from China. I was one of those people that got completely scammed by a China-based website selling wedding dresses.
You absolutely could not tell that the site was Chinese and the reviews on the site itself were excellent. I completely fell for it (and to this day, feel really stupid for it). Turns out, the reviews on the site were fake: the site doesn't allow you to give a review for less than 5 stars and they obviously delete any reviews with bad notes. My dress arrived and was indescribably poor. It was stained and literally falling apart. It took me months of trying to get my money back, and I only got part of it back once I threatened to contact my credit card company and report them as scammers. There was no phone number to call, and they would ignore your emails. They tried every excuse in the book to not help me: language barrier, it's a holiday, the manager will get back to you, blah blah blah. I would be absolutely terrified to ever make a majorly important purchase like this online ever again.
If you Google search some of these Chinese wedding websites, satisfied customers are absolutely the minority. That isn't to say that NO ONE gets lucky and gets what they ordered, but why would you want to gamble like that? You have virtually no recourse, no protection. Even if it's only £200, do you really want to bet that?
THIS ASIDE, whoever pointed out that you have NO idea what suits your body type until you try some dresses on is absolutely right. If you look through the planning threads on here and talk to brides in real life, more often than not, they end up with a dress completely different than they originally thought would suit. If you buy a wedding dress online even from a reputable company, if it's custom made, there's no returning it if it doesn't suit you. Some sites like Phase 8 and BHLDN I believe have some flexibility with returns, but something made to order doesn't.
I think the cons outweight the pros.