Hi Guys,
Managed to capture M83 between clouds last night. Lazy me can't be stuff unscrewing the UHC-S filter and it turned out red. lost details from adjusting the colours. So "NO", don't image galaxies with UHC-S filter
Eric I found the UHC-S filter to be very benificial for me imaging galaxies with the DSLR but to me it was more of a light polution filter I was using it as.
The DSI would already be more sensative to the red channel then a slightly modded DSLR.