I may be wrong here, but I think of the verb "will" as in the set phrase "if you will" as an actual verb, with the rare sense "wish, desire, want", not as a mere future marker. Therefore, in this sentence:
- He wasn't very bright, or kind of a dummy, if you will.
…the "I you will" part can be replaced with "if you want to me to put it in a different way".
But I've heard some people replace "will" with "would" for some reason. Hence:
- He wasn't very bright, or kind of a dummy, if you would.
To me that sounds kind of strange, as if what you meant were "if you wanted to put it in another way". But what do I know, may be "would" would sound more polite or something, even in a phrase like "if you will", rather than just the past tense of "will".
So the question is: Is using "if you would" instead of "if you will" in the sense of "if you wish/want/like" technically "correct"? ("correct" as in proper according to the original use of "if you will".)