Great Planes Electri-Cub...

I wouldn't go less than 100W/lb. As a reference my FunCub weighs 2.5lbs and uses a 3s 2200mAh Lipo battery with a 30A ESC. The motor is a 3516 840kV brushless driving a 13x6 propeller although at sea level a 13x4 would be adequate for a training aircraft. On a 13x6 this setup delivers just over 300W. More performance is available on a 13x8.5 but still not unlimited vertical.
I have recently changed the motor to a 1100kV equivalent, this delivers 410W on a 13x6 and gives unlimited vertical, however some control harmony is lost, the throttle is a bit 'all or nothing'
After writing this I realise that you may not have sufficient clearance for the propeller since IC engines tend to use smaller props and higher revs.

As I put in the other thread, you do not HAVE to fly at full power. That's what the throttle stick is for!
Do you drive your car with the go-pedal jammed to the floor?
Excess power is good on a wet grass field, (or off water) as you can 'blast' out, but then ease back to a more sensible rate.
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The best way to decide what motor to put into your Cub is to complete the airframe, add the radio gear, fit a battery of (say) three cells and the biggest capacity that will fit into the available space, then weigh it all.
Having got that figure, you can look up a motor that gives the 100 Watts per pound, on three cells, and see what amps and prop the manufacturer advises, and add in the weight of THAT motor, to see if it still matches. (the actual flying speedo 's added weight will be negligible).
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You don't have to buy the HobbyKing motors and speedo's - but when you look on the motors pages, most of them give weights, dimensions, power drawn, rpm's per volt, prop size to match, etc, to give you a good start-point. (some even have the i/c size equivalent) Don't forget to get a speed controller that is 50% bigger than the motor calls for, so you aren't running that at gut-busting levels!
If you are too mean on the rating, you 'can' fry the thing on the take-off climb-out, and then suddenly you have no radio or power!
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Scale flying appearance is all well and good, but you cannot scale down the air molecules! So your model is in effect flying through treacle.
Trying to fly too slowly causes you to lose control response, and the model can/may/will go all waffly, as it is trying to stall. Loss of directional stability, and/or wing rocking, is one of the signs of stalling. How the model is balanced affects what happens next.

This E-flite Power 25 (EFLM4025A) has been recommended as a suitable replacement for a 600 can motor, but from what I remember the OS10 revs at about 17k+ you would need a 1400 or 1500kV motor with a 3s battery to drive an 8x4 prop, unless your undercarriage will allow a 12x6 then you can use an 850kV

As an aside, using your equipment in it's mid range is going to give a much longer service life than running at full chat for most of the time.

Specialbuilder wrote: So, using a 100Watt/lb motor should enable me to fly at half throttle whilst still retaining a decent amount of control?
I appreciate the wick can be turned down, but then to keep the analogy, I could have a 2 litre car, but the 1.5 is still perfectly capable.
Martin

Exactly right on both counts Martin, but the 2litre is going to last longer and be much more comfortable on long trips (quieter) although the cost of ownership is slightly higher.

Controlability is set by the speed of passage through the air, not throttle setting.
Otherwise a glider would have no control, as it doesn't have an engine to throttle!
Speed through the air on a powered aircraft is set by the rpm's, prop pitch (and diameter), and attitude.
Remember the old saying - point the nose down, it goes down, point the nose up, and it goes up a bit, then down!