There Are Pandas, and Then There Are Pandas.
And this isn't either of them! The Pandas we're talking about here, are watches, not bears. And what got me thinking about them (again) was a link posted this morning by @cm.rook who pointed a few of us to the very attractive (and not terribly priced) Yema "Rallygraph" Panda which, in it's most traditional arrangement, looks like the one on the left, but can also be had in the version on the right: The model on the left is a true Panda, while the model on the right is called a reverse Panda. The reason for that distinction is clear--Panda bears, only come in the first arrangement. Now at this point, everyone should be thinking about the most well-know Panda, The Rolex Panda, which is actually a Daytona, and among Rolex Daytonas, the most famous of which is the Paul Newman Daytona, which was famous first, because it was Paul's, and second because it sold at auction for $17.8 million (US Dollars). The story of that auction is well-known so I'll only...
Nov 8, 2019
I currently live in Hong Kong, with riding experience here, in SG and Thailand. Personally, no way would I use a jacket like this in Singapore, NO membrane jacket breathes enough for the tropics. If you keep riding through a rainstorm, all the rain does is cool you off a bit.
I do have various eVent or GTX jackets. They are saved strictly for non-tropical environments.
Or just hold up a couple of different types of jacket up to your mouth and try to blow through them. A simple nylon shell, a WPB shell, maybe a softshell. That should give you a very good idea of how well waterproof/breathable fabrics do for permeability.
True microporous membranes (like Event) are generally the most breathable in the real world because they work by actually letting air pass through the holes of fabric. But they don't let much through, so even though they breathe relatively well, they will still steam up inside if you are sweating a lot. You can tell if a membrane is truly microporous by, as RockyMountains says, seeing if you can blow air through it.
Monolithic membranes like Hyvent or H2No (at least the cheaper versions) are generally made from a solid layer of polyurethane which does not allow air to pass through. They "breathe" (read: transfer moisture) via molecular wicking - essentially the water has to be diffused through the material and then evaporated away. These membranes may perform well in lab tests but in reality they are generally far less breathable. They work best in cold, dry environments.
The hybrids like Gore-tex use a microporous membrane with a thin monolithic membrane for protection. This is because skin oils degrade the PTFE (Teflon) that the microporous membranes are made from. Because the monolithic membrane is thin it diffuses moisture more quickly than a typical PU membrane, but still does not allow air to pass through. Although the newer Gore Pro is claimed to be genuinely microporous.
While most people find that microporous membranes are superior in terms of breathability, they also can temporarily lose breathability due to clogging of the pores. Fabrics with monolithic membranes like Hyvent or Gore-tex won't have this issue, although they can still lose breathability from wetting-out of the face fabric. All WPB fabrics benefit from being washed regularly.
Bottom line: you may find the a microporous membrane jacket keeps you less clammy/more comfortable for longer than a monolithic or hybrid membrane. However, no membrane (so far) is breathable enough to keep you from steaming up if you are sweating a lot.
I love it but have wondered if there is something better out there, since it's now relatively old. Since I get wet from running, it seems the best option is whatever would dry the fastest and not leave me feeling soaked when it is a downpour. I feel it's performed incredibly well in this regard and I tend to tie it around my waist when I warm up, and it drys quickly that way. The more I think about this and related your comments it also seems this is only relevant to me to avoid getting cold. If it was warm and raining (a situation I have not experienced yet, which is kind of crazy), then I'd probably not use a rain jacket but no idea if it was something really long (10+ hours).
For short, high activity environments, I just rely on shelled microfibre, treated with a water repellant. My body heat pushes moisture out faster than it get get in unless it's a torrential downpour, in which case I'd probably be getting wet anyway. I wouldn't rely on this for mountaineering or multi hour, obviously.
A step up from this would be to look into UK Paramo clothing, which is rated for waterproof. It is a very different paradigm to standard WPB fabrics though so the idea hasn't taken off in the US.