Kwanpen are very well made and for that I don't mind buying something made by them. However, if I wanted to go for a Kelly/Birkin design, I would rather get the real thing than an "inspired" one. You need to think of these situations as these might lead to awkward/embarassing situations in the future:
1) Friend/family/colleague approaches you and compliment the bag, then ask you, is this an Hermes Kelly/Birkin?
2) Would you carry this bag into an Hermes store? What if an SA ask you about the bag?
If you're comfortable to tell them there's this brand called Kwanpen that mades Hermes inpired bags in very good quality, and you really love the bag and will enjoy using it, then you have an answer already. On the other hand, if you think that might make you feel uncomfortable then perhaps it's better to get the real deal, be it exotic or leather.