Prophet 5 filter would certainly be most welcomed. According to Arturia's P5-V manual, their implementation is based on the famous SSM2040 filter chip, which is one of the best sounding filters ever, and overall my favorite 4-pole lowpass filter. SSM2040 definitely has a distinct sound that makes it unique. Besides the P5 Rev.1 & 2, it was used on Voyetra 8, and SRM Cat by Octave Plateau (later known as Voyetra). By the way, check out Voyetra 8 on youtube :
http://www.youtube.com/watch?v=XHJbUShzbXgHeavenly analog sound...
Later revision Prophets employed Curtis CEM3320 chips that were also used on a number of other vintage analogs (Pro-1. OB-8, Elka Synthex & more...). These chips are generally regarded as inferior to SSM chips, but like anything to do with music and sounds, it's all in the ear of the beholder.
As far as oscillators go, there is nothing particularly special about P5 rev.1 & 2 oscillator.
Those revisions use SSM2030 oscillator chip, and its waveforms and behavior are not that distinct. It was replaced in later revision Prophets with Curtis CEM3340 chips, and guess what... we already have it at our disposal, because it was also used in Jupiter 8 which Arturia has already implemented ! As far as Oberheim SEM oscillator, it's a discrete circuit (no custom chips) that is not very temperature stable, with saw, pulse & pwm. Again, as far as Origin goes, it's probably not worth implementing, as it's not as unique as say Mg or CS-80 oscillators. I think it makes sense to model these in virtual versions of Prophet and SEM to pay out most attention to detail, but as far as Origin, I think the existing oscillator models can be substituted with great success. Maybe Arturia could put some of their efforts into implementing a "different" type of a sound source - perhaps something along the lines of Karplus-Strong algorithm / physical modeling, which could easily be implemented on Origin.
I think, in conjunction with already existing modules, it would unravel a whole new world of sounds and spark more interest in Origin...
P.S.
Ckeck out Karplus-Strong implementation on a very cool sounding Accelerator synth by Radikal Technologies :
http://www.radikaltechnologies.com/accelerator_sound_examples.htmlI love guitar solo on Performance Check1 example... Sounds like something Yngwie would play...