I have looked into this and have heard some real positive reviews.
http://www.aerostich.com/jackets-pants/transit
I second that, and can contribute my own review.
I bought the Aerostitch 'Transit' leather jacket and pants combination 3 years ago when I visited the Aerostitch facililty way the heck up at the far west end of the Great Lakes. Ironically, I was going there to get fitted for one of their one-piece textile suits, but after trying on and carefully inspecting the Transit outfit, there was no doubt, the Transit was the one for me.
I've since travelled about 30,000 km (18,000 miles) with it, and I am very happy with it. It is extraordinarily well manufactured (as it damn well should be, for what it costs, which is close to $2K with taxes), it's built like a Swiss watch. It is 100% waterproof... I have ridden through some prolonged monsoon-like thunderstorms, and stayed warm and dry. It is also quite comfortable in summer weather - I have no problems wearing it on sunny days in temperatures up to about +27?C (85?F). Once it gets warmer than that, though, I switch to a BMW 'Airflow' outfit.
The leather surfaces are perforated all over. This does a very good job of letting air penetrate and preventing me from getting hot. But, the GoreTex that is everywhere within the garment keeps the water out as well as the best rainsuit ever would.
I'm not sure what the minimum temperature it would be good for is, because I've not had the opportunity to use it in cold weather. I'm going to guess it would be adequate down to about 10?C (50?F), perhaps a bit lower than that if it was a sunny day.
It is a very thoughtfully designed bit of kit, with pockets and vents in all the right places, and large swaths of bright reflective material on the back of the jacket and at the bottom of the pant legs. It is well-armoured in the back, elbows, knees, thighs, shoulders, etc., but the armour fits the garment very well and I don't get the feeling I am wearing an armoured garment, as I sometimes do with the BMW outfits. Both the jacket and pants have held up very well since I bought it and shows no signs of wear at all - it still looks new 3 seasons later.
Because I went to the Aerostitch facility to buy it, I had the opportunity to try on multiple different sizes until I found the size of top and pants that fit me perfectly. It turned out that the sizes that fit me best were one size larger than what I would normally buy (for example, if buying jeans, or a suit jacket).
All in all, it's a hell of an expensive purchase, but a purchase I am very glad that I made. I'm totally satisfied with it, and it has become my preferred riding outfit, displacing 3 other BMW outfits that I have. I recommend the Aerostitch Transit outfit without any reservation to others.
Michael