A Song of Ice & Fire Fans discussion

I am in a reading conundrum, and I need some help. What should be read first, A Dance with Dragons or The Mystery Knight?
Apparently, the third of the Dunk and Egg novellas provides some further explanations for what we learn in ADWD. That would mean reading The Mystery Knight first.
But, on the other hand, I don't want to read -yet- a story containing potential spoilers for book 5. That would mean reading ADWD first.
Do you see my problem?
Has anybody read both and can put me out of my misery?

In my opinion you can read in any order you want. I think it's just a theory(this possible spoiler you mentioned).

I have not read The Mystery Knight but it was published before ADWD so i don't think there are any spoilers for A Dance with Dragons there. The story is set long before the events of ASOIF so how can there be spoilers for the series there?

Fair point. Maybe more than 'spoilers' I should call them 'strong hinters' for things that happen 100 years after Dunk & Egg. You know GRRM, he either kills your favorite character when you least expect or returns him/her from the dead when you expect it even less. And then hints at the reasons 3 books later.