ok. i have two G6’s. one purchased directly fr/GG, the other from BPL.
each is slightly diff. from the other.
the older one fr/GG has three webbing loops on each of the shoulder straps – primarily/originally intended for routing a drinking tube (two loops on the outside & one on the inside of each shoulder strap – this one also has more of the “pack cloth” on the bottom)
clearly, i use the webbing loops to loop the bungee through – this prevents the vert. slide you mentioned if the Platys are stowed Adv. racing style.
if carried down low, gravity just pulls them down as far as possible. i can slide them up to the buckle & then remove them from the bungee. reverse the process, somewhat, to stow them again.
on the newer G6 purchased from BPL, i made loops of 1/8″ bungee & looped them through the doubled over sewn webbing that holds the shoulder strap buckles on. this keeps the bottles from sliding vertically. the bottles don’t really get in the way of the buckles since my thumb & fingers enter from the outside to loosen the shoulder straps.
Platys are carried down-low in an identical fashion as on the older G6.
BTW, on the older pack the inside webbing loops on the shoulder straps, together with a bungee & an Altitech II (with carabiner type of attachment) serve as a poor-man’s sternum strap. on the newer G6, another length of bungee looped through the same area of folded-over and sewn webbing and the Altitech II form sternum strap. the carabiner of the Altitech II is used to “join” the loop at the end of the bungee to the webbing loop on the older G6 or another small loop of bungee on the new G6.
due to the very rocky, uneven terrain i’m often on, i find the pack more stable if i “kludge” up a sternum strap.
was this explanation clear?
haven’t tried this, but for a light duty (low tension) sternum strap, i bet you could sew some lt. wt. webbing loops to the webbing b/t the buckles & spin fabric shoulder straps (or just loop the bungee through the folded-over and sewn webbing holding the shoulder strap buckles on – just like described above). then, you could use some 1/8″ bungee to form the sternum strap. no Altitech II to join the two sides of the bungee sternum strap together? just take one length of bungee & tie it to the newly sewn on attachment webbing loop and make a small loop on the other end – just large enough to squeeze a mini-toggle through (don’t put the toggle in yet). take another length of bungee & do the same on the other – except the free end, you might attach a mini-toggle by passing the bungee through it & then knot the bungee to prevent it from pulling back through the mini-toggle. now you can “thread”, so to speak, the mini-toggle through the loop at the end of the other length of bungee. tension can be adjusted by drawing the knotted end bungee further through the mini-toggle. the idea here is similar to,…what’s it called?…a Stadium Coat (???). you know, those 3/4 or full length hooded wool coats with a series of wooden toggles that pass through loops to close the front of the coat. you prob. have seen these – they were more popular 30-40 yrs ago.
you know, i’ll have to look at the pack upstairs (i’m in the den downstairs typing this – no pack in sight) to be sure, but you might even be able to “sacrifice” a bit of the velcro opening by sewing 1/4″ to 1/2″ wide webbing loops to the lower end of the velcro opening in the shoulder straps. the velcro would serve as sufficient reinforcement to prevent tearing the spin cloth. use 1/8″ bungee as the sternum strap. use a mini-biner, AltitechII, or the bungee loop & mini-toggle arrangement to secure the two lengths of bungee-sternum-strap together. the 1/8″ bungee when stretched (if sized the right length) exerts minimal stress, so i don’t think you will do any damage to the pack fabric.
[Belay this last suggestion. just checked my newer G6 pack. the lower end of the velcro opening is a bit too high – unless you like your sternum strap higher. On me it would be mid-way b/t the “nips” and the hollow of the throat. way too high for my tastes. not sure where it would be on your pack, but prob. too high also. Stick with how i implemented the sternum strap on my newer G6 – use the folded-over sewn webbing holding the shoulder strap buckles on.]
the purpose of the “poor-man’s” sternum strap is just to lightly keep the shoulder straps from sliding off the shoulders when bending & twisting. it doesn’t take much to keep them on me. also, if you are a “chest” breather (like most adults) vs. a “deep abdominal” breather (young children, martial artists, Zen Buddhists, Tai ji quan practioners, etc.), then the bungee also allows easy chest expansion.