Testing for these next!
EDIT: yes, you can one-shot clear with 648; testing 647 next. Also as far as 94 rarity from methodical, initial calculation suggests around 631-633 perception (I noticed 475-477 perception gave 94 on methodical with a cap of 539, a difference of 62-64. the one-star cap being 695: 695 - 62 = 633; 695 - 64 = 631) I will gear for this and try on the next set of nodes.
EDIT 2: for the legendary nodes: 647 is a 1-shot clear; 631 perception was 94 on methodical, 141 on methodical with discerning eye, 84 on impulsive (ran out of attempts to try impulsive + discerning eye). My data suggests that the lowest possible might be 630, so I can try again with 630 but that might require some remelding, and 629 would drop it down to 92 if my calculations are correct.
EDIT 3: Just tested methodical again with 630 and 634 perception on folklore node: both came out to 94
EDIT 4: Tried again with 629 and 635 perception. 629 was 92 on methodical; 635 was 96 on methodical.