RE: Is bigger always better?
As a second plane, the Tiger 60 is just fine. It's what I had as my second after the trainer, which was a Hobbico NexSTAR. The Tiger 60, for instance, is very easy to control, although it does fly somewhat different from the high-wing trainer with a lot of dihedral. In fact, I would almost consider the Tiger 60 as a low-wing trainer!!
What I did was I flew the Tiger 60 for a few flights with an instructor who was there to help me with the harder parts of getting used to a low wing aircraft. This permitted me to make minor mistakes with the instructor there to correct them and show me what to do. After three flights with an isntructor, I had it pretty much under control.
That was several years ago and I still have the Tiger 60 and still fly it.
Larger is not always better, under certain circumstances. Some of the more advanced aircraft are not as forgiving upon approach and landing as the Tiger 60 is. Because of the wing design, short fuselage, they require a rather fast approach and landings are much more exciting as with a slower plane such as the Tiger 60.
There are others that qualify as 'good second planes'. One such plane is the Sig Four Star 60. It is very similar to the Tiger 60. You must consider that the larger planes are more visible than the smaller ones and those with large wings with good wing loading factor, will give you soft and smooth performance, yet can do all the neat things that the other, more aerobatic planes can do.
Pattern planes, in the 90 size range (Excelleron 90, Venus II, and so on... I mention those two because I have them and fly them on a regular basis now) are very smooth and rather easy to fly because they are very stable and fly straight. But, they can be somewhat difficult on landing because they require a faster approach than a trainer, or even planes like the Tiger 60. They go where you point them. Bank left 30 degrees and they will stay there... that sort of thing.
The U-CanDo is a very nice plane, on the order of the pattern planes that I have but considered more 3d'ish than a Venus II for instance. It is faster than a trainer, can be made to be very responsive and agressive, but toned down a bit to give you something to move up to by changing the throws, for instance. But, starting out with a 'low wing trainer' type aircraft is a good way to go. It will give you the training needed to handle a low wing plane. Remember, that the U-CanDo is a mid wing aerobatic aircraft, as are most of those high-performance aircraft.
Best of luck with your next choice of aircraft. Let us know what you come up with.
DS.