Not true. Diameter is only .007" difference. The 284 win is not based on a 30-06. The only similarity of the 284 win and 30-06 is the same bolt face.
The 284 is a great mid size cartridge even if it's the wrong diameter by .007"
my dad has a 284 win and it shoot great. The problem is that brass has been non existent since he had it built 2 years ago. Most of the companies have suspended making it since everyone wants their creedmoor brass that probably brings in a higher profit margin.
After seeing your time crunch for this year I'd stick with your 6 and work on building a new rifle for next year.