If your 120 is in good shape I really wouldn't bother. My 2022 150 is nicer to be in than my 2005 120, but I think 95% of that is new car smell, v 17 years of use on a farm

If the 120 wasn't so rusty underneath and I was constantly worried that the rear cross member would come off when I was towing I could have happily stayed with it. The 150 does seem to do much better on fuel, comfortably 35mpg v 26/27mpg in the 120. But the 150 has already done a set of injectors in 10,000 miles so I am yet to be convinced of its longevity.
As it happens I've just started pulling the inside out of the 120, and taking off the bumper and body mounts to have a good go at rust repairs, and the rear member is in surprisingly good condition compared to the rest of the back half of the chassis.