^^Interesting that you can fit a 15" laptop into your PT. I can't comfortably zip my PT with a 13 inch MacBook Air in it, at least not without seriously distorting the base of the bag.
Here are some comparison pics I took with my MacBook Air vs a Courier, Work, City, PT, Velo and Day.
My 13.3 inch MacBook Air vs a Work and a Courier
In a Part Time
In a City
In a Velo
In a Day
In all, I'd have to agree with the earlier posts about NOT using Bal as a laptop bag. Get a laptop case/bag to put your laptop in. If I have to carry a 15 inch laptop all over the place, I'd just use a backpack - more comfortable.
1. While the Work and Weekender (WE) are big enough to put a 15 inch MacBook Pro in, the weight can be quite hefty when you factor in the weight of the usual stuff you lug around. Carrying it on your shoulder or in your hands will not help matters, because the weight is not evenly distributed, and probably give you a backache.
If you intend to get a GH Work or GH WE, the bag itself is already quite heavy (at least compared to their RH counterparts), so you definitely would not want to carry an extra weight in the form of a 15 inch laptop in it and make yourself miserable.
2. It's a matter of personal preference - while the Pom Pon and Courier can fit a laptop, I'd choose not to use them.
The Pom Pon has a circular base which means there's no place where my laptop can 'rest' against, like it does in a bag with a rectangular frame like the Work for example. That irks me as the laptop falls all over the place.
The Courier is quite an unstructured style, where the leather just folds upon itself and falls into a squishy puddle. When you add in a laptop, the aesthetics are spoilt. Plus if you carry the Courier crossbody, the presence of a laptop makes the bag stiff, and it doesn't hug your body as well, making it uncomfortable. That irks me too.