Smaller bezel and lower weight will make iPad 5 more portable but not as mini. Some say that they use their ipad mostly into their houses so they don't care about minis portability and prefer the bigger screen of ipad 4... but guys you cant compare it with minis portability... i use ipad mini everywhere and i mean everywhere even in my toilet... while walking around home with one hand... and most of the time while in bed. Using the mini with one hand in the bed is so much big difference compared to ipad 4 where you have to find each time the perfect position in order to use it and after some minutes is difficult to continue using it without your hands getting tired. You just wake up and grab it with your one hand in any position you are in bed to check your social stuff.... with ipad 10" you simply cant do that so easily. iPad 5 will solve some of these practical problems but in the long run i think people will return to their ipad minis with retina screen or not.
I carry my iPad 3 with me everywhere. I have always used a case and every case I have owned allows the iPad to be easily put in a position, even in bed, that only requires one hand to balance it. Right now, I use a Bookbook case and just swing out the back cover and put my hand on top to balance it.
As for portability, I have a Scottevest jacket that can handle it without an issue. There are a couple huge pockets that it can slip in. In the summer, I don't wear pants that would make the mini any easier to handle. I would still have to carry it in a bag or in my hand. Nothing different in this area.
The trade off in screen size would be a downside in every app. I usually want the largest display with the best screen I can handle unless I need the device to be pant pocketable and the mini isn't. I carry an iPhone for that purpose.
I should admit that I have large hands, so that may be the key, but my mom and niece have small hands and I have never heard them complain about their Original iPads being too heavy or too big.
That being said, if they can make it smaller and lighter without sacrificing screen size, I don't see any trade off. Although, that alone would not be a compelling reason for me to update. If they made improvements to the screen, added apps I use that made my iPad 3 feel too slow, etc. would be better reasons for me to update. I am pretty happy with how it works now, though.
I am not bashing the mini. I thought Apple needed to enter that market. I just see very little benefit for my personal use.