I agree with HF, the smaller buckets are excellent for mopping up, and should still have a place in the scheme of things. However, advances in bucket design may obviate this, eg the DUFAS with it's variable fill and multi drop. We used the DUFAS last season, and it was quite impressive both from the flying point of view, and for the troops on the ground. The ability to vary the fill according to aircraft weight and performance, then the multi drop capability which is ideal to deal with mopping up currently the domain of the 206. A long line is essential, even with 100' the BK's downwash is intrusive, but it may lead to less reliance on smaller machines.
Clearance, I'd modify your assertion that Victorian's have led the way. Media publicity aside, there are pro's and con's to the current reliance upon belly tank equipped mediums, to the exclusion of (almost) all else. Prime example would be last season's Alpine extravaganza, where support to Mt Hotham was extremely limited, and when it came as a bucket equipped 412, there were hours of support preparation required. The nearest water source (Swindler's Creek) at the bottom of the valley (c. 5200' amsl) would have been no problem for a bucket on a long line, but was no good for the 412. A buoywall had to be taken to Hotham, erected in the car park (at 6000' amsl), filled via the snowmaking pump system (major drain on resources at the resort to achieve), all for 3 hours bucketing. IMHO, a more flexible use of available assets may often produce a better result.
No argument that a belly tank is good over the urban areas, but the dogmatic approach leaves little room for variation. How often would a bucket on a medium or long line be able to access a water source denied to a the (short) schnorkel on a belly tank machine? Often enough for it to be an issue, in my experience, especially if the belly tank machine has to increase its transit distance and times as a result. For the bush and parks areas that comprise the major land mass of NSW and Victoria, the belly tank concept has severe limitations, especially in times of drought. I've lost track, are we 5 or 6 years into the current drought?
Just my two pennyworth
