From what I've experienced. this is what we can say
Does size matter?
The bigger the tablet, the harder it is to stroke. The stokes performed by the hand physically is now longer, and even with the right texture nib, the wanted stroke line is harder to come out 'right', With an A4< pad, I usually repeat the stroke atleast 5/6 times to get it right, for this reason i have ctrl+z on as a short cut on the wacom utility button. I think I therefore prefer using smaller tablets and zooming as necessary. Those buttons on the bamboo make this sooooo much easier, the scroll wheel can be set to zoom AND rotate the canvas while another button is set to pan (as default setting on most software), and as the shortcuts are already in your utility buttons, once you get used to it, it will be as natural as moving and rotating a sketch book by hand.
2 of my house mates had el cheapo tablets, forgot the brands but one of them was horrendous, the refresh rate or something was not right, quicker strokes comes out as angular set of lines, the drives often drive the CPU to insanity, and to top this off, it was falling apart and had no buttons or scroll wheels on the tablet it self.
I've not tried the Bamboo seriously (only in shops), but I would suggest giving it some time, and getting used to drawing on the wacom fully using those keys and scroll wheels and see how you feel. Obviously if you get the chance, do try different brands, but i'm sure you will just appreciate having wacom sensors more.
and remember, drawing on the computer is not the same as drawing in real life, comparing the two is a rather hard task by it self due to the uncountable amounts of positives and negatives of both.
I hope this helps.
Finally, the house mates i lived with were all Students, so none of the opinions were professional. But we all agree with our findings.
I mean, from the short use i had on the Bamboo, i couldn't feel much of a difference. (needs looking in to though)
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