I tend to prefer to only put animals of very similar size together. When you have one larger than the other, the smaller one will always lose out when it comes to competing over hiding spots and so forth. Males should really not be housed together, even though they seem to be doing just fine, it is inevitable that hormones will take over at some point and one will get hurt. Tails grow back, other parts don't.
Every gecko has a different personality. Some of mine don't mind being held, others prefer to be left alone, and some run for it when you get close - even though they were all raised the same. Some just never get over their fear of humans, or simply don't like being picked up.
Rav