Giving up 37g and dual piston, but saving how much money?
None. Because I already bought and have been using the GT-Fs. Lol
But…for all of you still weighing options:
Juin Tech GT-F: $280 CAD. Natively designed for 160mm. 4-piston. Comes equipped with pads, as well as a spare set. Comes with 3 sets of bolts for different chain stays. 332g for the system including mounting hardware
Available on AliExpress
Onirii BR-05: $125 CAD (for 160mm version). Natively designed for 140mm. 2-piston. Comes equipped with pads. Comes with 3 sets of bolts for different chain stays. Comes with some cable crimps. Comes with 160mm adapters.
369g for the system including mounting hardware.
As of posting, only available on Taobao.
A note on Taobao: It can be used internationally, but you need to be able to read Chinese, or have a friend who does. It accepts international credit cards, and shops internationally - at least the vendor I bought the calipers from did.
Buying is a two-step process. First you need to buy the item. This gets you domestic shipping (free in my case) to the nearest port in China.
Once it arrives, you receive a notification to arrange international shipping. If you bought a bunch of stuff on Taobao, you can wait for items to aggregate at the port and have them shipped together. If you have a ton of stuff, you can arrange things to be shipped by ocean freight (at least as far as I could tell)
Most of us will just get Cainiao shipping (or whatever retail option is available). This cost me $40CAD and is included in the price above.
If you don’t pay, the item just sits at the port. I don’t know what happens if you let it sit there forever.
Then, you can sit back and wait for the package to arrive. All in, it took about 3 weeks from purchase to door for me.