For what it is worth, a lot of the semi-auto shotguns I have seen have problems cycling lighter loads. That is the only reason for recommending the O/U over a semi-auto.
I agree, if you get more serious about it an O/U is a great gun to have. Until then, You can learn a lot about technique by getting a 28" barrel for the gun you have.
Agree on the $30 vs $2k scope comment. That said, the quality increases quickly all the way up to the $500 level, and then only incrementally beyond that. For a .22lr, spending more than $300 -$400 would be crazy.