I recently purchased my first Chanel from MGFT after following her for ages and just waiting for the right bag to come up. Similar to WheresMyChanel, I also lucked out with my bid and woke up with the pleasant surprise that I had won. I ended up falling in love with a black vintage mini 20cm square flap which looked LUSH, and it's a series 1 with both the sticker and authentication card!
I found the whole experience excellent and very easy, to be honest. The Instagram stories with the bag showed me everything I needed to know, and for this particular bag she also posted stories of the one in her own collection and how she uses it which really convinced me. Bidding process was super simple, and she was very helpful and responsive with the next steps after winning. Transaction process and payment was very smooth, but I was able to pay directly to the TransferWise account in pounds which may have helped simplify things. Shipping was a dream - the bag arrived in the UK from HK in about four days, and it was packaged perfectly (bubble wrap, tissue paper, dust bag, the works), she even separately wrapped the chain from the body of the bag to avoid chain marks in transit. As for the actual bag, the condition is just stunning and even better than what I expected - I've posted pictures.
I'll admit I was a bit nervous about buying something off Instagram without seeing it in person but she is so passionate about vintage and was so clear and responsive that I really felt taken care of. I would definitely buy from her again.
Hope this was useful for someone! Happy to answer any questions.