Notice that my mixes cloud up a bit around 250-600Hz? That is inherently the "punchless mud" area. But that is where mastering engineers should be compressing/cutting but at the same time not sacrificing dynamics as much. Since the dawn of loudness mastering I already gave up on mixing thinking of the full range approach. My answer to that is bordering on mud so that when things are pumped up in mastering, HINDI MANIPIS.
all the things you said about mixing though ... hmmm ... i have to admit ... i dont get it. sorry. you mean you purposely put the mud there for the mastering engineer? sorry if my feeble brain can't catch up. i havent really worked with a mastering engineer before but as far as i know i have to make my mix as clear and as articulate as possible almost leaving nothing for the mastering engineer to do but raise the volume to a more "commercial" level. i mean if he finds a better version of the mix then great for both of us. but i will not put mud there to keep my mix from "thinnning" out during the mastering stage. i have to asusme that a good mastering engineer would not ruin my mix that way. parang mga doktor dapat sila, first do no harm. diba? im sure my mix can still improve in thousands of ways and maybe the best thing to do is to communicate to the mastering engineer what i think my mix lacks in the first place. or leave a buffer somewhere. when i first sent my mix to shinji, he said it was a little dark, which i thought would be great for the mastering engineer to work on. anyway, i gave in to the temptation and finally applied a master buss eq (precision mastering eq), and voila ... it sounded nice right off the bat. i could hear the wooden snap of the snare a lot better this time. in restrospect i didn't need to wait for the mastering engineer to make my mix sound satisfactory. my values are still geared towards doing the best i could for the mix, starting at the tracking stage up to the mixing stage. if i must slap a buss compressor and buss eq on the master channel then so be it 
emily lazar is the mastering engineer and proprietress of one of new york's finest mastering houses. when asked about what kind of mix was best for mastering she answered "it should be deep, wide, and tall."
First of all, here are some points I wanna raise:
1. One man's (or in your case, woman's) warmth is another's mud.
2. Monitoring environments vary so greatly that some can or cannot feel the warmth that boosting lower frequencies can do.
3. Analog days are over, so that inherent fatness around the low mids and compression around 2KHz is not the thing anymore. Ika nga, "2k is the new 10k".
4. When I say "mud" up, what I really mean is fatten up the low mids because once you raise the volume to a more commercial level, what I notice is that the highs and high mids get more pronounced, but due to this loud mastering trend, a lot of lows and low mids get cut.
I do track WITH compression AND EQ, boosting around 250Hz and 500Hz because they seem to give a little buffer for the mastering process. During mixing, I also add a tad more of those frequencies then send them to more soft-knee compression. In the end, I hear the tracks more integrated, and not very separated.
I also like to add: "MASTERING IS THE ART OF COMPROMISE..." - Bob Katz
