Is iOS all that matters now?
Lets hope not! As much as I love my iPhone 4S and having got an iPad for my daughter; I still find the MacBook Pro to be one of, if not the most important product of the bunch in terms of being the 'only' Apple product for the must have essential combination of both maximum power and portability (with emphasis on raw power more than battery life because as one has the freedom to take a MBP from room to room & building to building, they can still plug it in to a power-source).
Also with the advent of the impressive Thunderbolt Display, this has provided a means to use a MacBook Pro as both an invaluable portable machine and of course have the advantages of plugging in a large high resolution quality screen that most desktops enjoy, when hooking up to the Thunderbolt Display back on the main desk... except for the apparent fps problem encountered above.
I know the problem won't be fixed in a hurry, in fact it may not be addressed at all on our current models which is leaving me to consider the next soon to appear MacBook Pro 2012 model. I shouldn't have to resort to spending yet more money on yet another MBP (would be my fourth one), but if I'm not going to get the smoother frame-rate I need for both 3D games and 3D applications then the Thunderbolt could be a rather expensive White Elephant investment if the already 'not brilliant' frame-rate of my Macbook Pro is further hampered and reduced when using the Thunderbolt Display in clamshell mode.
Incidentally I believe your right about mirroring having recalled trying that before, but must confess I like having MBP in clamshell mode for less distraction and protection in case the rare event of a drink or something being knocked over/spilled; I don't mind renewing an Apple Bluetooth keyboard but not a whole MacBook Pro 😉
The games I long to play with smooth frame-rate are mostly Battlefiled 3 & Battlefield Bad Company 2 in Bootcamp as well as many others within OS X... If I am forced to consider the soon to be released MacBook Pro 2012, then I really hoped they've further increased the Graphics processing power as the 'holy grail' for me (and many others I would imagine) is to run the big Games/3D applications with high detail settings at a continuously maintained top smooth frame-rate so as not to get that nauseous strobing effect and if this could be done at the Thunderbolt Display's maximum resolution, then it would be effectively matching one-on-one pixels on the display's LCD panel thus getting the best possible effect. This might actually be possible if the 2012 MBP is to inherit higher resolutions (2880x1800) for retina display, then theoretically the Thunderbolt's slightly lower 2560x1440 resolution may help performance better. I really hope we'll see at the very least a 2GB video RAM card on the newer models, but who knows? As long as I can finally get a maintained smooth high frame rate on my Thunderbolts max resolution, then I would be finally happy.
In the meantime, if an update/patch is released soon to help the existing fps problem even a little, then that would be most welcome!