yeah
(btw my main idea for it is really simple, heldkeys[arpsequence[row]]. well, sorting the new note-ons needs some tricks to keep it fast, also handling of notes in the phrase, since it could be recorded live. but imho it’s not hard to do, so i think, the renoise developers will surely add an arp at some time. x)
I think this concept of having held keys define the exact notes that playback in a phrase is great not just for arps but for phrases in general - ie, load up a bassline phrase, hold down a few keys and have the phrase playback exactly as you want to within your song! This could be great for live use and also a really efficient way of auditioning/trying out different phrases whilst putting a song together.