Congrats on the purchase buddy, even I had gone to the store with the intention to purchase a DSG jacket but ended up buying the Alpinestarts TGP-Air jacket. Just to add a few pointers to the product
I) It does come with a rain liner which does the job pretty well even in heavy rains. I have worn the Jacket always for my Bangalore - Mysore and reverse ride home on weekends during the rainy season. Total of 6*2 rides, encountered heavy rains 5 times and my Shirt was not really wet like when I wear a normal raincoat. The jacket also dried within an hours time. Since this is my first riding jacket cannot really compare it to any other jackets , but I found it above satisfactory.
II) Back has a foam padded protector as already mentioned and is upgradable(recommended upgrade since I found it to be fragile and easily bendable nature)
III) The jacket is much lighter than the DSG jackets I had tried on.
IV) It comes with Velcro straps at the waist level and for the arms also and can be easily tightened to necessary levels.
v) The rain liner which is black in color makes the white color on the jacket look dirty even when the jacket is well cleaned.

Thanks for the inputs bro! Haven't really used in rains since there are none in and around Pune..
What I'm really worried about is its usability in Winter rides, as I'm gonna do one in January, Pune - Goa.
Did you by any chance happen to ride in early morning in cold weather.??
Since this is a mesh jacket, I was thinking of wearing a fleece later inside for thermal insulation..