"Also I would like to keep weight to a minimum if possible."
IF that's the case, I think you're going in the wrong direction with the two underlevers. Underlevers almost ALWAYS weigh more than a same powered break barrel. The Beeman R-9 or BSA Supersport have about the same power as the TX-200/HW-97. I just weighed a few guns: TX-200HC .22 with scope 10.5lbs, HW-97 with scope 10.25lbs, R-9 .20 with scope 8.75lbs, R-9 .177 laminate stock with scope 9.0lbs, BSA Supersport .22 with scope 8.0lbs, and a R-1 .20 Carbine with scope 9.75lbs.
If weight IS an issue it would be easy to see I'd recommend an R-9 or a BSA Supersport. Even the more powerful R-1 Carbine would weigh less than either if the two underlevers.