I’ve generally found that if you are trying to sell to a dealer then any modification negatively affects the price. If you are buying then it has less impact.
Condition is one of the most important things rather than age. If it’s a DT10 then some of the early ones with lower case writing had double discharge issues, the later ones with upper case Beretta on the action are a better option. The cross bolt should be sticking out a bit from the action and the top lever to the right of centre.
Great guns I have one myself which Tim Greenwood modified for me, a little bit off the comb, reshaped the grip, and took the barrels out to 5/8’s in both.
Don’t know why I don’t use it now as did some of my best shooting with it. Like messing around with different guns too much to my detriment.