That's a nice series of images mate, so flexi monopod or not you've got some sharp nature shots for your efforts.
I had a similar fliex issue with my monopod after picking up the K-1, particularly when used with the 150-450. I went out and picked up one of these:
Manfrotto MVM250A Aluminum Video Monopod with Fluid Base MVM250A
I really like the foot unit for the added stability, however I forgot when buying this that I'd planned to go down the beach to capture surfers and I didn't think sand would work well with that tripod so I picked up one of these:
Manfrotto XPRO Over 4-Section Aluminum Monopod MMXPROA4US B&H for those times where I might damage the other monopod.
The load rating for both (17.6lbs) is plenty for the K-1 (3.95lbs) and the 560 (6.7lbs) even with a sturdy gimbal head, most of which weight between 2-4 lbs.
Tas