So if you are an I, you'd become an E, If you prefer F, you'd rely more on T............yeah you get it, a swap.
The thing is, it's a trial basis. so, let's say, maybe after a month, you'd switch back to your original preference. A month is probably a good enough amount of time to experience fully whatever letter you trade in.
Oh yeah, you can trade in any combination as well, so if you want to trade in you IS for EN, that's perfectly fine.
So, which would you trade in? Would it be one? Two?, maybe all 4?