If he didn't use invisibility then how did Queen have the time to react to Sanji disappearing, commenting on it and looking for him ? He even said he disappeared "again", the first time referring to when he did it when saving Momo (which Queen noticed by his own admission), and mentioned Judge's experiments. Also the way Oda drew it makes it pretty clear, he didn't draw those "speed lines" he usually draws to highlight a character moving at high speed, Sanji just disappeared smoothly like water evaporating. Just compare that to the CP0 agent using Soru a few pages earlier, the difference is clear enough.
I guess invisibilty in base allows him to disappear for a couple of seconds only, wheras the suit allowed him to be invisible continuously. When he attacked Page One, he turned invisible before attacking him and was still invisible during the attack, but against Queen, he stopped being invisible before landing his attack.