Canon IS/DO lens

[streep]

Question,

My Canon 70-300 IS/USM is now 15 years old, and that is starting to show.
Softness and not very sharp on the edges above 250mm. Time for a replacement !!

I am very happy with the range 70-300. I notice I use the 70-90 range a lot so dont want to upgrade to a longer lens.
My equipment has a lot to suffer as I travel a lot and use a backpack.

15 Years ago Canon introduced several lenses with 'Diffractive Optics', including the 70-300 IS/DO
Smaller than the USM and L lenses of the same range. Lens review sites often write that the results are almost as good as with the L lenses.
They are no longer produced but are frequently offered second hand in good condition.

Does anybody here have experiance with these lenses ??
My main question is : Are they more durable or less durable then the USM or L lenses ?
For the size, quality and price I am looking forward to buying the DO, but if it is a fragile lens I am better of simply replacing my 70-300 IS. replacement.