It's stressful enough having to leave every 3 months to renew the visitor visa. I couldn't imagine having to do it every two weeks. Also, we, and others I know, have run into problems in that immigration is not accepting many visits to and from Macau or Schenzen to renew visa's. We now go home or away for 3+ months at a time to minimize the amount of entries stamped in the passport. If you get flagged thats it...
Also, with regards to the extended visitor visa, this is a one off thing. If you get approved its not like you'll be able to go back when it expires to get a new one.
Really, the only way for things to work in HK long term is to get married otherwise the stress will become too much of a strain on your relationship.