Have to say the guys on here told me the Guideline was no good (too high out the water so wind caught it etc) so I ended up with the Shakey. However, if I had the choice again, it would be the Guideline, hands down.
The reason, I used a Guideline from one of the guys in the Pike Fly Fishing Association (almost to a man they all have guidelines) and I found for bigger waters it was much more stable than the shakey in a chop, sitting higher up, actually out of the water was much warmer, and when hauling line, your left hand/elbow does not end up soaking wet. It was also extremely comfortable with none of the slipping forward all the time that you get on an unmodified Shakey.
Although wind did possibly affect it a little more, I found it MUCH easier to turn into the wind and hold station than the shakey, probably as you only have your legs in the water you are not trying to push against most of your torso as well.
Lastly, going through weed and over shallows was a doddle!
However, for a first tube on somewhere like Haddo, the Shakey is fine, although in reality its not a 5 bladder tube, but a 3 and a half as the smallest bladder needs to come out else you are pushed too far forward, and the "back rest" bladder is quite small..but still safe
And as said by everyone..get a life jacket!