Stability of Seat Pack? Viscacha particulary!

[cfi on the fly]

I am brand new to bikepacking and thought I was onto something very novel and of my own until coming across this site.  While reading through the forums I came across several pictures of peoples seat packs and it looks like they are able to jimmy rig or outright buy a seatpack that does not require an external frame.

I really like the looks of the  Viscacha by Revelate Designs.  My question is just how stable is this seatpack.  Is there very much lateral movement?  I just recently purchased a seat rack and strapped a sea to summit big 13L dry pack on it - see pic.  I use every square cm of the dry pack and need something at least that big.  I am wondering if the seat rack is just unnessary weight if a pack like the Viscacha is just as good?

Comments and reviews?

Thanks.

[bmike-vt]

http://www.bikepacking.net/reviews/bikebags/epic-designs-seat-bag/

http://www.bikepacking.net/reviews/bikebags/carousel-design-works-bags/

to start

[BigPoppa]

I have had my Revelate/Epic seat bag (the large size) packed to the brim for a multi-day snow bike race and I have it on my summer rig currently. I've never had problems with sway.

[VABikePacker]

I went on a group ride and let a person in that group borrow it - he packed it pretty "large" and it stayed nice and steady...

It's quite a bag - VERY well constructed.  I seriously doubt you'll be disappointed in it....

[trebor]

seat bags are typically very stable if not packed too heavily. soft stuff like down, socks, shirts, etc.

when putting in heavy stuff make sure they are to the seat post, not the roll top end. i've seen some sway a bit when packed rear heavy.