These steps lead to a strange result:
1 in empty patch, create new message
2 create a second new message (in the vicinity of the first one) and write int it: x 5
3 click outside
4 change the x into pitch by selecting the x in the message and start typing pitch
Because of the recognized prepend method of the nearby message object, upon typing the letter p that will be suggested and put in place where you're typing. However, continuing writing results in that the last two letters of prepend remain as something goes wrong with selecting. At the end the message reads: 'pitchnd $1' instead.
Since the switch to max 6 the autocompletion for messages, apart from the above error, has appeared to be obtrusive in quite a number of situations. Sometimes without noticing, I end up with messages that are not intended. For instance try to write a b c (or b c d, or f g h) in a message that is near another one. Suggesting methods while typing are really useful, but it would be nice if the actual autocompletion for messages could become a preference that can be unset. Scrolling with the arrow keys to a suggested method would work fine enough. This is not at all an issue for objects.