Maybe? That depends entirely on your particular tune.

Yes it can, but like Krama said it depends on how tight your speed is at without it. In the DWJ calculator just factor in the change. 

You can see the total the Area Bonus gives you in Character + Total Stats then set it to Demon Lord or just do the math lol. 

If you add speed to your CB team through passive sources like Great Hall/Area Bonuses/Faction Guardians and your comp goes out of a range that's absolutely necessary - think unkillable comps - then yes, that would absolutely have an effect on your comp. 

I would advice against using the Speed option for ClanBoss on the second half. There are in my opinion better places to raise first. 

I invested most of my points into Hydra areas (especially Resistance), some in Fireknight speed and some for ClanBoss in Attack and Crit Damage...

Would only put any of my medals into Clan Boss if incredibly necessary to finish off a one key comp, really.

Hydra/important (harder to gear) end game dungeons and that's really it, I think. 

Yeah, with putting points into CB, I tried to compensate for the loss of half our clan members in the last months...tried to be more helpful in downing the CB.

Otherwise I would agree with you....

Understandable. Just saying for general advice for folks looking to maximize Area Bonuses long term without doing a million Live Arena fights. 

It would have totally screwed up my team.  i put a few into ignore defense and haven't needed 2 keys since even on force.

Now you have me curious to check out Live Arena and see what I have been  missing.