Update:
Now arrived! It took about 3 or 4 weeks for QC photos to come through, but once I approved those the shipping was fast.
I'm pleased with it! It has all the pros and cons that people have described: the main con being that the way they've done the easXchange bracelet means that the first couple of links angle downwards quite sharply from the lugs, making it sit quite funny. I'm not sure, but I think the gen version is similarly fixed in place, but doesn't angle down so sharply.
I have tried a gen on once, but only briefly, so I can't really say how it compares to gen. One thing I wonder is whether the rep really has AR coating on the sapphire. The crystal seems to be VERY reflective - but I don't know whether that's just normal for a domed crystal, even with AR coating. Similarly, I noticed that the very tip of the minute hand appears bent downwards - but again this is probably the curvature of the crystal creating an illusion. I have heard others say that the colour matching of the dial to gen (blue) is not quite right, but without comparing side by side not sure.
I ordered the strap as well as bracelet and am glad I did. Although I'm sure it's not great quality, it's convincing enough that I'm enjoying wearing it on the strap - maybe even more than the bracelet, considering the first link angle issue already described.
All in all - a good first rep-ordering experience so far. It's going to give me a dilemma over what gets more wrist-time: this, or my Sinn 556A (the latter having cost me three times as much as this IWC...). At least with the Sinn I could swim with it with confidence...
Not sure whether I'll keep buying reps or not. I'm guessing I probably will get at least one more. If I do, I'll definitely stick to reps that are very close to NWBIG - I think anything less the differences would bug me too much. I'd buy a BVF Cartier Santos 35mm without question if they could sort out the floating R. Another rep I have my eye on is the 36mm Clean Explorer. Thanks to all for the help in the process!