And regarding gearboxes that has both manual and auto functions,
there are 2 kinds..
1) The automatic transmission with manual override..means it's a
torque convertor/CVT transmission, but they have a function for you
to override it and up/down gear manually..this is to give you
greater control over speed and engine braking..
But usually this kind of manual override in an automatic gearbox
won't hold a gear at the redline..it will still shift up at the
redline for most auto box with manual override function..some will
hold gears at the redline like a true manual box though..one
example is BMW's auto box with manual override function..it'll
really hold on to the gear at the redline until engine overheat and
kaput..(or maybe it'll shift up when it sense the engine
overheating..I also not very sure.. 
)
2) The other kind is robotised manual gearbox, one example is BMW's
SMG..it means it's actually a true-blue manual gearbox, but the
clutch is automatic..means the engagement and disengagement of the
clutch is automatic..all you need to do is to up/down gears..and if
wanted, it can also act like an automatic gearbox..meaning it can
also shift gears automatically and you don't need to do
anything..
But one thing about robotised manual boxes..the upshifts are
usually never smooth like an automatic gearbox..but if you can ease
off the throttle a bit duing upshifts, it'll make the shift
smoother..but technology has improved to a point where it is really
very smooth in automatic operation now, but will still feel a bit
of jerk..just like when you are changing gears in a manual car,
very hard to make an upshift in a manual car smooth..
So go decide for yourself which kind of gearbox listed above you
would like to get.. 
Edit: typo..
