The above may be a wind-up, but here goes....
Niles,
What's the problem?
IFR flights have been climbing and descending through the levels of VFR flights in class G for years. There has never been any serious alerted see and avoid in this - many IFR ACFT at TOD or altitude change just make a call to Centre for IFR traffic, not all make a location/atitude/intentions call - and even if they did, at many locations conflicting traffic may not hear it because they are on an adjacent Area frequency (e.g. descent into Mudgee from the south)or they just hadn't changed from their last frequency yet. I am not aware of midairs occurring in Australia because of this.
I don't use Jepps, but what paperwork are you referring to? Is it the estimate for next reporting point? Just give a value based at departure time plus flight planned estimate and correct it en-route. Simple. No need for fancy calculations on climbout through the more populated CTAF/MBZ and lower levels of G. If you really don't want to do any math, just get one of them new-fangled GPS thingies TSO'ed and otherwise (the Garmin III Pilot is great for instant multiple en-route estimates once in cruise - even betterthan the GNS 430 for this purpose!!).
BTW, IFR flying is not just the domain of paid pilots - many folks with CIRs who are fond of living and returning home to their families fly carefully and responsibly for business, as private ops.
Personally, I'm not particularly fond of NAS - it seems unnecessary change without justification - no-one has come up with convincing explanations of the proposed cost savings....but we're fooling ourselves if we think IFR ops in class G are really any more protected now than they will be under NAS. Roll on ADS-B!
Safe flying
NOtimTAMs