Hello... my name is Fred, and I am a Yankee frugal gear whore.
Oh man... is this question right up my alley. I have tried multiple approaches to the questions raised here about all purpose gear, and every one of them results in some sort of a compromise.
Being a native New Englander I don't do so well in the summer heat. My wife and I each have a set of Olympia Air Glide 3 mesh jackets (in HiViz) and Air Glide 2 pants (Pewter Gray). In the brief summer months these are a very comfortable mesh setup and, as others have said, on a chilly morning you can just layer under them and stay relatively warm. What they are not is waterproof. The "waterproof inner liners" are not really good enough for a full rain day. So that means you have to carry some sort of over the top rain jacket and rain pants if you are going somewhere for more than a couple of days and can't predict the weather.
Unfortunately when you are on tour for several days is exactly when you really don't want to spare the cargo space to carry around 2 sets of rain gear. And then when you do have to don said rain gear over the mesh protective gear that can be downright hot.
For touring we also both have Olympia AST jackets (also in HiViz). Hers is an AST1 mine is an AST2. We also have solid textile waterproof riding pants of several different makes. My favorites are a pair of old Olympia Ranger 2 pants that are looking very long in the tooth and aren't quite as waterproof anymore. With the solid gear we do not need to carry any rain gear, but when the temps soar above 90, like they did on the high plains of Wyoming on us 2 years ago, things can get very uncomfortable.
I have two copies of Aerostich Darien jackets that I am really starting to love. I bought them both used as the ticket price for this gear new is pretty stiff, and I wasn't sure I would like it. I have a HiViz Yellow Darien Light that came complete with extensive street cred (dirty), and another older version of the regular weight Darien in gray made back before they improved the collars.
Even though they are solid textile and GoreTex lined, I find these jackets to be every bit as cool in the summer heat as the mesh gear. That's because you can open the neck area and the sleeve zippers for forced "ram air", and open the pit vents and back vents for exhaust, and you set up a constant flow of air over your entire torso. I've been riding on days in the high 80's or low 90's and been very comfortable. And of course you can zipper these jackets up, and throw on an extra layer or electric heated liner and you are good in the cool weather too.
One of my problems with these Darien jackets is that they are too long in the front, so I end up having to do the "Darien Roll" on the lower front part of the jacket after I sit on the bike. Otherwise the fabric bunches up and pushes the jacket up around your shoulders and neck. The other issues are my own doing in buying used: The HiViz is disgustingly dirty, the Gray one is clean but has the stiff old collar design, and both of them are a tad bit too small to layer properly for the cold. I bought them 44 / Large when I really need a 46 or XL to be able to layer up fully.
I wrote a suggestion message to Aerostich and suggested that they incorporate a new design in either their Darien, or some variant of touring jacket in the future, where they should make the front shorter (like the Roadcrafter) and leave the back long like the current Darien to eliminate the need to do the tuck and roll but still get great rain coverage. They wrote back and thanked me for the idea, but I haven't seen anything like that from them yet. When they do, I'm going to plunk down whatever it costs on one and sell off my old Darien jackets, probably for about the same (short) money that I paid for them.
