Brian, First of all, your tests confirm my findings on UV and IR response of an unmodified G1.
I hacked my first G1 for this very purpose. Unfortunately, I did a silly mistake and wrecked the SD card slot (which is flimsier than any cell phone SD card slot).
I did remove the UV/IR/AA filter stack. I can see in IR very well.
The modified G1 cam:
IR response is about +2 stops (Hoya R72) responsive than the stock G1 (ie., relative to the Visible reading) about -1 with a Heliopan R780 and about -3~4 stops with a Heliopan R1000 filter.
UV, I am having real trouble with judging the response. There is clearly UV response but
it appears (need to verify this) to be less than the corresponding Olympus E-410.
The NMOS sensor (on a flex board) has a permanent glass cover, the filter stack goes on top and then there is a thin protective glass cover that also serves as the ultrasound dust shaker.
I have to figure out if the flex board cover glass (that would be bad) cuts UV or the Ultrasound shaker cover glass that cuts UV.
Self modification of G1 (or GF-1), as I find, is a bit too much to chew for my abilities.:banghead:
I have another G1 purchased specifically for this purpose (another kind gesture from Robert Campbell here)....