Yes, in general,they are good.The olds tubas around this size are usually good too.A 3 valve BBb with reachalbe,long, 1st and 3rd slides can get you a long way.Both available on ebay right now...
Pensacola Symphony
Troy University-adjunct tuba instructor
Yamaha yfb621 with 16’’ bell,with blokepiece symphony
Eastman 6/4 with blokepiece symphony/profundo
The 12j is the 3 valve version of a 5j(4valve).The 12 and 5 are BBb.The 2 and 3j's are CC.The 2 is near identical to an Olds BBb.All of these play well and are usually to be had fairly cheaply on the used market.A new 5j is a bit overpriced IMO,compared to other horns available in the 4k range(i'd probably look at a HOJO in that price/size class in a new BBb).I'm not a false tone guy at all,so I can't really comment on that...
Pensacola Symphony
Troy University-adjunct tuba instructor
Yamaha yfb621 with 16’’ bell,with blokepiece symphony
Eastman 6/4 with blokepiece symphony/profundo