The Nine Eagles Free Spirit Micro (or Solo V1) is indeed a very good indoors (only) helicopter.
I`ve seen it in action, I wanted one.
But it is too small and looks like a toy (although it is not).
Add to this that it is a expensive and so Iended up on a cheap indoors toy, a Syma S107.

On the other hand if you really like to go outdoors then buy a Big Lama.
I have some, I like them. Notice that it does not like wind though.

The E-500...
Hmm, I`ve seen it on the shops.
It is smaller than the Big Outdoor Lama.
So immediately lost any interest on it.

Modding a Big Lama.
I think only your imagination can limit you.
But the "needed" upgrades are: heatsinks, extended inner shaft, lots of batteries, a second charger (to speed up charging proccess).


PS. Sven this red one looks even better!