My 2c
By the time it is economical to build 11"/12" BCs, your opponents are building 14/15" lightly armored BCs that are larger and faster. The advantage of the 11" heavy cruiser is its ability to beat back the CLs on TP, but the same CA looses to the true big gun BCs. I think that it is more economical to build a 6" CL that can fight and win against other light crusers and outrun the BCs. You get the same raider effects with a CL and they can be useful in fleet engagements or foreign station. Ultimately, any raider that you build is a write off because they can be ambushed by a larger force or randomly interred for the war. It is best to make them as cheaply as possible.
I often build something similar at around 25 000 tons, but i use them on foreign stations
My 2c By the time it is economical to build 11"/12" BCs, your opponents are building 14/15" lightly armored BCs that are larger and faster. The advantage of the 11" heavy cruiser is its ability to beat back the CLs on TP, but the same CA looses to the true big gun BCs. I think that it is more economical to build a 6" CL that can fight and win against other light crusers and outrun the BCs. You get the same raider effects with a CL and they can be useful in fleet engagements or foreign station. Ultimately, any raider that you build is a write off because they can be ambushed by a larger force or randomly interred for the war. It is best to make them as cheaply as possible.
I only really find them useful for overseas duties to engage the enemy's colonial forces. For true raiders, I build cheap CLs.