Cost, loss of velocity and voiding of the vendors warranty... Why would you be looking at an over sized line? In nearly all cases it's the other way around (a.k.a. changing from R22 to R410a) Please give the other factors in your particular situation so that a meaningful answer can be attempted. Are you feeding a TXV or a fixed metering system? Height and length of the run? etc.
Just trying to understand what the problems would be with an oversized line? Create your own scenario and explain the possible problems. As you mentioned "Txv or Fixed" would the potential problems differ for each system and what would they be? Please explain?
If its a heat pump you can count on charge imbalance problems from season to season. I dont think there are any, if at all legitimate reasons to oversize the liquid line and then complain of poor performance or reliability of a unit. mfg's go through great pains to develop and test the tables and since they did that, it would be best to heed the tables and consider them accurate, there is no + or -.