I've been doing some duck hunting along the Rio Grande, all jumpshooting. Currently I have been using a SXS Ithaca 20 gauge (unsure of measured barrel length; not long enough.) I'm looking to buy a new shotgun for next season, and I'm considering another DB. Wondering who uses Over/Under vs SXS, and what your thoughts are? I've considered a semi-auto, but I find I most often can do much better shooting two rounds, reloading two more and getting four shots off as opposed to loading three more shells into a semi auto (based on experience using buddies semi auto remington)

That, and I really enjoy shooting double barrels, so I'm not looking to buy a semi. Mostly considering CZ shotguns, I have lots of CZ handguns and am pleased with them...And they offer 25% off for military/LEO, so....Thought? O/U or SXS?

Find a used browning citori.

This

I just bought a bobwhite 20gauge.  Heard mixed reviews but the price is right and I am co-located with CZ here and they have a good warranty.  I'll let you know after I pattern it.

If you are set on using an O/U I'll echo the previous statements and recommend a used Citori.

If you're considering a pump at all, I've been VERY happy with my Winchester SXP waterfowl.  Supposedly one of the fastest pump guns on the market, comes in RealTree Max 5 and durable as hell.

$341 from Buds in Max 5 but I think you can order in shadow grass as well.

https://www.budsgunshop.com/catalog/product_info.php/products_id/82369/Winchester+512260291+SXP+Waterfowl+4+1+3.5%22+12ga+26%22