Hi Nanthiel,
Your choice DB-455 looks pretty nice. It can be used as messenger/laptop/camera bag.
The question is, what are your gears?
Do you want to carry them all at once or just one at a time?
Are you sure you want to carry laptop and camera with big lens at the same time?
Unless you have a very strong shoulder, that setup might hurt you in the long run.
For me when I travel light with just a body plus one short zoom or 2 primes, I use Lowepro Rezo 160. A very nice small bag. Highly recommended.
For medium size, for ex: 1 body + 1 lens FA* 80-200/2.8 and flash OR 2 body with 6 primes/flash, I'll use my Tamrac. I forget the model but it looks like this one:
Tamrac - Model 608
But, last time I used Tamrac carrying the big zoom plus body is really hurting since I got only support on one side of shoulder while walking around for almost 3 hours.
So, I just recently purchased Kata 3N1-30 to carry my most gears.
Yes this bag is bigger but not too much.
I tried it in the store and like it. It gives so much support & weight distribution to your both shoulder and waist.
So back to your need.
If you're not planning to carry more than a 16-50/2.8 lens + body + flash.
I think you've made good choice with that DB-455.
Consider this weight:
- laptop 15 inch approx 6-7 lbs
- body K20D approx 1.76 lbs
- zoom DA 16-50/2.8 approx. 1.24 lb
- Flash 540 no battery approx 0.8 lb
TOTAL approx 10lb (no battery yet)