I've run the gammut on gear bags and I've come full circle back to the Nova 4. Personally, I don't see myself going back to more expensive bags.
First, the fancy bags are really great but a common bitch I had about them is none of the bags with snorkels truly seals the bag up. You always have to pay attention to whether the snorkels have crept open and that was constantly a worry to me because I had a vision that my $3K investment in mics would someday slip out of the bottom of my bag out one of those goddam snorkels. I've lost lots of little shit out of the snorkels in the past...mostly batteries and things like mic stand adapters, but enough that it FREAKED me out about losing something of high value.
Second, all the fancy bags come with lots of shelves and pockets. For me, lots of shelves end up just getting in the way and taking up space. OK, maybe if you're really particular about keeping your gear in 100% tip top shape, lots of shelves help to keep stuff from banging against each other in the bag. But I don't keep my stuff in the bag 100% of the time...pretty much only when I'm out to the show. When I get back home, I take it all back out and pack it up for storage. The shelves end up taking up ALOT of space inside my bag. If you're worried about banging, wrap stuff up a little better (put mics in the cigar cases), etc. but the shelves are a waste of space IMHO.
My Nova 4 has minimal shelving and maximum space savings and best of all NO F***ING SNORKELS. I can put everything I need inside it and still zip it up solid before and after the show so I'm 100% for sure I'm not gonna lose anything out of the bag.
The nice bags have the window on top...OK that's nice, but completely non-essential. At the show, you usually end up setting levels and leaving it. I usually cover the bag up anyway to protect from spillage, regardless of whether there is a window. So what's the difference between looking through the window or opening the top flap of the bag to check levels every so often.
For the OP, if you're finding the Nova 5 to be too small, I think you should find the magnum, but don't bother with the designer bags because you'll pay tons for them and they won't have enough space. If you have so much stuff that you need a magnum, then you'll start losing shit out of the more complicated bags anyway.
BTW, it's not just the snorkels that you lose shit out of. The PEGZ bags don't seal very well at the top and neither IMHO do the porta brace bags.
I'd also consider is getting some clips (like the mountain climbers use) and buy some cordura/vinyl bags with zippered tops, or getting some Crown Royal felt bags, and start securing the less expensive stuff to the strap of your bag and carry the expensive stuff on the inside.
For example, crown royal bags make perfect wind screen holders and since the screens will be hanging from the outside of your bag, you don't have to worry about them getting all deformed in the inside.
I'd think you could keep all your clamps hanging in a bag on the outside too. Lots of clamps are great, but I like keeping them quarantined from the rest of my gear because they're the most likely thing inside my bag to marr up the surfaces of my recorder, mics, etc.
Obvious space saver hardly worth mentioning is to carry your duct tape on the outside too...around the strap.
Also, after the show, use velcro straps to coil and secure your cables and carry those on the outside around your strap.