I also have the csr and here's my strategy
Use this card as a supplement card and spend on large dining, travel, and bi nights out in lkf. You'll get the 4.5% return (for travel) and have almost 0 fx costs. I also have USD savings and income so this pays the bills. However a tip for you if you have premier and global transfer to another hsbc location, the hkd to USD rates are quite good, like 15 pips off xe.com
For everything day to day, use the SCB Asia miles or the ba avios card and connect it to your octopus card for aavs. This will help you collect for alot of places that accept cash or octopus only (mtr, restaurants like la rotisserie, etc).
You may want to use the hsbc signature card to supplement spending in the lucrative categories such as groceries.
Hope this helps