I think it's possible to take advantage on near IR guiding without an ONAG if the proper IR filter is placed in front of an OAG camera. If I remember correctly Greg Bradley tried this and saw some improvement. I cannot find the thread but Gaston (inventor of ONAG) comments here:
http://www.iceinspace.com.au/forum/s...2&postcount=28
Peter
PS I have it on very good authority that a very well known company in astronomical gear will shortly release a kit of sorts to allow Sharplock type of focusing with OAG + IR Filter. Think of the possibility of never focusing for the night! Boggles the mind.