I recently purchased 2 G2's and am looking for cases for them also. I was looking at the case in the second link and liked how it is supposedly made by HTC. I tried looking on the HTC website for more info and pics of the case but unfortunately couldn't find them on their product website. I called and spoke to a rep at their sales site who was not aware of the case. I also spoke to 2 reps at HTC customer service who couldn't find any info on it either. This has me a bit concerned since I would expect HTC to be selling these cases on their own website if in fact they were made by them, and I would certainly expect them to be aware of their existence (which they were not). Not saying their not genuine, but I am a bit leery now.
On a related note, one of the HTC reps I spoke to mentioned they do not recommend cases or screen protectors as they can cause overheating problems, especially while charging the battery. he said if I was going to use a case I should remove the phone from the case wile charging the battery. With these snap on cases that seem to be a royal pain to take off this doesn't appear to be an option.
I saw in another thread here several users seem to like the EPIK TPU cases sold on ebay by DCMugen. Sorry I can't post the link since this is my first post, but there are a few other threads that discuss it and show pics. So this is what I'm looking at now since it can be easily removed to charge the phone and should be more gentle against the phone than the hard plastic. My only concern is how flat the screen will sit with the keyboard open. It's kind of hard to tell from the pics.