I've liked and used Kata bags for years. They make good kit, and I love the easy to find yellow interior colour they use.
I used my Kata Flyby-75 on a recent trip to Italy. It was small enough to be a carry on with Easyjet, and it's strong enough to sit on. It was also plenty large enough for everything I needed on the trip, including a full size DSLR with a 70-200 f2.8, laptop, Olympus OM-D with various lenses, and lots of space left over for chargers, batteries etc.
It's a good bag, but it could be a little bit better.
So I hacked it.
Firstly the included zipper pulls were a little bit rubbish, so I replaced them with bright orange DIY para-cord pulls. I used orange because it matched the colour accents on the front of the bag, and also because I like my bags to stand out so I can see them easily. Makes them harder to steal you see...
I didn't like the way the top of the case flopped back when opened. It needed something to stop it opening all of the way.
My fourth concept was the one that worked the best. It required drilling a couple of holes (in the tough plastic side of the case) for the cord, and making a few more holes in the fabric for the cord to pass through. Thread a single bit of cord through, tie a couple of knots in the end, and I now have a much better bag.