What is the easiest turret to interchange with rico (in gameplay) if you want to go back and forth?

Personally, I think that having the "crystal drop" system is best, because it's nice to have some luck in the game if you aren't playing too hot. Like I said, I'm not a big fan of this new system, but it is an interesting idea. Higher ranking people tend to like this update more than lower ranking people. Like Monkey8banana, maybe set the (crystal drop off/on) as an option on the settings for any battle.