You have narrowed it down to the same 2 companies I did. I just picked up my new DPMS Panther Classic Bull(.980 miked) at 9:00 this morning, at their factory.
If you will be scoping it, either a 16 or 20" should work well. You will loose some(little) velocity with the 16". I got the standard A2 configuration with a 20" because of the longer sight radius and because it is the same dimensions as my former M16 issued in the Cavalry.
It was no problem engaging the 330 yd(300M) targets with the standard peep sights. My Troop ran the range every month. In the afternoon, we would set the far targets on auto. After a couple sessions, you could maintain 100% hits(30-of-30) at 300M.
I don't think you can go wrong with either company. I will be shooting my new AR later this week, I'll let you know how it turns out. I think this bull barrel will really work well. I was issued 5 different M-16s while I was enlisted, all with standard mil spec barrels. Every one fired MOA or better.
Bushmasters have a chrome-lined barrel which target shooters dislike. It is impossible to get the exact same thickness down the entire bore. It is more of a combat application. Although there are accurate CL barrels. If you check out the Highpower competition board at [url]talk.shooters.com[/url], you will find few, if any, shooters using chrome.
DPMS barrels are not chrome-lined. This was one of the major selling points for me. I was geared more towards accuracy. Chrome lining is said to double the life of a barrel, but barrels are fairly cheap anyway, and we're talking THOUSANDS-10s of THOUSANDS of rounds.
Good Luck
[url]www.bushmaster.com[/url]
[url]www.dpmsinc.com[/url]