Delta_G:
Does your version with printf produce smaller or faster code? Prove it.
Forgot to address this part.
There is no such thing as "my version" of printf. I simply enable the use of existing functionality that the AVR-GCC compiler provides.
This saves me the headaches of using multiple "Serial.print" calls and makes for easier reading of the source code itself.
My IDE also has a checkbox which allows me at edit/compile time to enable or disable floating point support. Yes I know that it uses some resources, but when the sketch is compiled and floating point only adds 1.5K to my 24K sketch and it all fits with room to spare in an UNO or a MEGA, why should I beat my head against the wall to use "dtostrf" and all the extra work that involves?
Now, I don't know if enabling native floating point uses less or more resources than dtostrf and it's required buffer, but the difference can't be all that much and since I have room to spare anyway, why not?
My big gripe is with the DEVELOPERS of the Arduino IDE system. Sure, I understand that they want to conserve resources... I get it. But why not place an OPTION in Preferences to enable or disable certain features?
Want floating point? Just tick the checkbox.
Want to use printf? Just tick the checkbox.
Need every last bit of memory? Un-tick the checkbox.
But, GIVE THE USERS THE CHOICE AND CONTROL!!!
We can turn line numbering on or off, we can choose to auto-rename a sketch from .PDE to .INO, we can do a lot of other [sarcasm] really important [/sarcasm] things in Preferences.
But, control the things that EVERYONE HERE asks about? Nope, can't do it. WHY?
If you and I had a dollar for every time someone asked why trying to print a number only results in a question mark or how to get dtostrf working, we could afford to have others write our code! 
(although what fun would that be?)