Like your idea.

Why do you not want the experience books, have you reached the maximum level already? If so there is always the possibility that the hero levels will be increased again.

Energy packs are also sold separately.

I am not really sure about double hero, apart from that it can protect the town as well as helping with marches.

I wonder if it used to be different than it is now, or was envisaged differently, I read something somewhere about this recently.

No, not completely at maximum level, but selling Hero Keys along with experience books seems like a marketing ploy. You buy keys so you can allow your hero to level up, use the books and you're automatically at the next level and need to buy more keys. I don't mind doing tasks and other things to level up a little slower. 

Thanks.

You are probably right about it being a marketing ploy.

I have seen players using double attacks on ubers, and I do not know what the benefits are, nor the benefits of attacking two invaders simultaneously.

      HAVING THE HERO DOUBLE CUTS THE DESTROY TIME ON AN INVADER IN HALF, 

AND DESTROYING 2 INVADERS AT A TIME WITH 2 HEROES TAKES THE SAME AMOUNT OF TIME AS DOING ONE AT A TIME

BUT WITH MORE CLICKING BACK AND FORTH ON THE INVADERS.

Two points.

1st. Your thoughts.

Without doubt what you write is true, but not without its drawbacks, but for some players may be of little consequence to them.

It will be interesting to see what, if anything, is posted by others.

2nd.Your posts.

Although capitalisation of the text has some merit over those with tiny letters and no formatting at all.

Using all capitals is considered to be bad form, and I believe it is disallowed here.