On ocean dives you SHOULD HAVE a knife....it works well in the posiiton on a belt, both for the routing and for the access.
Most divers need a pocket. It needs to be out of the primary flow of water to keep the diver slick and hydrodynamic. The pockets we use on a waiste belt are perfect for this...they can hold the smb and spool you may need at the end of a dive, or any number of other small but essential elements you may need on some dives--and of course, they route well also.
I'm not DIR or GUE but I've found that the 'classic' Hogarthian setup is a well thought out COMPLETE system.
Cherry picking individual parts of the system can cause problems when mixed with other items which are not compatible with the rest of the system.
For example a looped 7' hose with a stage bottle mounted on the right hand side or a snorkel on you mask can cause problems with the hose getting caught.
In my case, on an IANTD Deep Air + Nitrox course I was disgusted at how difficult it was doing air share drills and securing a standard 40" octopus/backup 2nd stage when using a Jacket BCD. I had an instructor using a twinset on BP/Wwith long hose and bungee backup and was impressed with the ease that his gear config imparted to the same tasks. I started thinking about what I wanted from my gear. I did a lot of reading and watched the DIR3 video and found that the Hoarthian gear configuration made sense to me as a
system.
So then I went to a BP/W when I purchased a BCD. I then found I was still never happy 'managing' standard recreational length hoses. So I bought new hoses 7' and 22" for my regs and suddenly
underwater my hoses just seemed to disappear. I can deploy and stow the long hose without any effort and I always know exactly where the backup is. The 7' hose doesn't pull at my mouth. I practise deploying and stowing the long hose and swapping to the backup near the start of almost every dive because re-stowing the long hose is easy. With a 40" octopus on a clip I still find re-securing the reg to a clip a pain, and I can never lay hands on it without fumbling.
The 7 foot long hose 'just works'
for me. I'm a fairly basic open water diver and don't have a canister light, so my solution was to tuck under the pouch I was
already using on my right hip to hold my DSMB and spool. I didn't need to add gear to secure the hose - it was already there as I had needed the storage pouch and my wetsuit had no pockets. The interesting thing is that I ended up at the same point as Dan Volker suggests above.
Would a 5 foot hose work just as well for me - probably, I bought the 7 foot thinking that if it doesn't work for me I'll try a 5 footer instead. I never needed to find out as I like the 7 footer just fine. Though it might be an interesting experiment when time and funds permit.
Would a 7 foot hose be the optimal choice on a reg set which is loaned to students wearing a jacket BCD with nothing to easily tuck under and no experience or training with a long hose - unlikely. I can see a 5 foot hose being a better choice in this instance.
Two stages, one on each side - again this would interfere with the 7 foot hose routing and be less that optimal.
beanojones you've found that for your circumstances and considering the rest of your gear configuration a 5 foot hose works better. I don't doubt that you are correct. That doesn't make the 5 foot hose better for everybody. Nor does it make everyone using a seven foot hose a DIR zealot.
What does it all come back to - Matching the components you choose so that they work as a complete system and that your system matches your requirements.
Now, can't we all have a beer and get along? 
