A T1X rifle with a 20" barrel is 37.8" long. The 16" version is 33.7" long, less than a yardstick. Both are less than the average height of a 4 year old child in Canada.
In the scheme of things, a 20" .22LR barrel isn't really a long one. In the not-so-distant past 20" would have been considered a relatively short barrel.
There's the idea in vogue today that the shorter barrel will give faster average MVs (it may) and that faster MVs is an advantage. There is no advantage to faster ammo when it comes to accuracy performance. The most practical advantage to a shorter barrel is in jurisdictions that allow the use of suppressors.
The bottom line is that best way to decide which barrel is best for a shooter is by evaluating how the rifle balances, at the shoulder and in other circumstances.