Louis, I have some guitars that
really like to be tuned down a whole step - they just come alive. I put mediums on those, and drop by one-half step (Eb) or more often a whole step (D). But I make sure to capo two and let others know that I am NOW at standard pitch
and announce the key. Tuning a whole step makes certain songs much easier for me to sing as I get older. I have a two octave plus two note vocal range, from low F on the bass string up to an A (fifth fret on the first string). More reliably I have a two octave range, from F to F, but if I am warmed up the extra notes come back.
It is easy enough to capo up one or two frets, but if you are tuned differently, you have to transpose on the fly - it's hard to "capo down".
Having played my 416 baritone a reasonable amount, I'm slowly getting used to thinking in terms of other keys and shapes. But nothing is easier than following another player's hands on an unfamiliar tune. It was unkind of your friends to not tell you in advance they are not tuned to standard. Surprise!! Now you know to ask ahead of time. It gets nearly impossible if they tune to something other than A= 440 Hz. Then you are not a discrete half-step off, but something in between.