What's the difference between V-るうちに and V-ているうちに?


My grammar book says: "V-ている is used more than V-る, but the pattern V-るうちに is
sometimes used." Is there a difference in meaning or style between the two?
When are they not interchangeable?

> 最初は美味しいが、{食べる／食べている} うちに飽きてくる。

> すべての少年が一度は胸に懐き、だが現実の非情さを {知る／知っている} うちに諦め、捨てていく幼稚な理想。




Very hard question.

For the first example, {食べる／食べている} うちに飽きてくる sounds exactly the same to me,
especially when you intend to mean "you get bored of it after a while (in a
single event of eating that food)". If you want to say that "you get bored of
it when you eat it too much (repeatedly eating the food multiple times in your
life)", I think the former fits better, since the latter has a stronger
emphasis on the "while eating" aspect.

For the second example, I think only the first one works. 現実の非情さを知るうちに諦め... It
is still possible to say 現実の非情さを知ってい **く** うちに諦め... which sounds a bit more
natural to me than the former. But the difference is very subtle.

