Well, this thread exploded lol...
Disagree.
I'm lucky enough to know some of the individuals who coined the "IIFYM" term on another board and it was NEVER intended to be used as an excuse to eat twinkies all day.
It was designed to deal with the bullshit issues associated with the "clean" eating philosophy like not eating dairy (healthiest protein around), not eating fruit (PACKED with micronutrients), not eating too much fat (80s "clean" included not eating egg yolks), not eating carbs (paleo & "clean" have become synonymous now), etc.
So when questions like "Should I eat the whole egg?" or "Can I add cheese to my sandwich" would come up...IIFYM would be the answer.
My point is - you can eat healthy on IIFYM.
Your "feeling better" point is completely subjective - I know plenty of people who felt like killing themselves on "clean" diets. As Roush alluded to earlier, its about finding what works best for that specific individual.
As for the water/bloat issue, its not caused by high sodium per se but rather the fluctations in sodium intake. Honestly, I don't even see how this is a problem unless your a competitor/model or just a complete pussy who needs to man up and not worry about a few temporary water pounds
I work with plenty of competitors/models and 99% of them follow IIFYM year round except for the final 2-3 weeks of contest prep or within 3-10 days of a shoot where we manipulate a bunch of variables to get them in the best condition possible.
The 1% exception are individuals who simply don't have any self control - if they have room in their macros for a couple of chunks of chocolate, they will get the taste, lose all sense of logic, and consume the entire pack and then some more if available. These individuals do best on strict meal plans to avoid any potential "triggers" BUT, even here, I work hard at improving their relationship with food so that meal plans will no longer be necessary...its a long term (years) process as anyone who has dealt with eating disorders will tell you.
You don't have to take my word for any of this either, the usual Youtube celebs (Ogus, Hodgetwins, Gregg O'gallacher, etc) all follow IIFYM and look pretty damn good, as do the majority of natural bbers like Alberto Nunez (Google him & tell me he has issues with bloat LOL).
I've said this before at the other place but there is no such thing as "healthy fat loss". The mere fact that you have to be in an energy deficit means your going to missing out on micro nutrients regardless of what your macros may be or how "clean" your eating.
Multivit ftw.
The data on fat metabolism is piss poor (for now) so anyone claiming that a fat is "good" or "bad" doesn't have a damn clue what they're talking about

Get a nice mix of all of them (something that will happen if you set macros properly) and be done with it.