The site only has 1-phase electricity; 3-phase requires a digital phase converter. For this discussion its pricing will be considered 1 (one).
Two chillers could be 1-phase, either 3-ton and 5-ton or 2 5-ton. A few offer a reverse cycle option. Right now, only one reverse cycle model offers an inverter-powered compressor (Daikin), however by next year 1 or 2 more should (Aermec, maybe Multiaqua). Cost ranges from 2x to 2.4x for 1-stage chillers, 3.6x for reverse cycle chiller with inverter-powered compressor.
One 8-ton or 9-ton single phase chiller has been identified from Drake. It has two compressors for 2-stages. Cost is 2.4x.
Carrier has a 3-phase 10-ton with a Copeland Digital Scroll giving 13 stages down to 20%. Cost with phase converter is about 3x.
Aermec and maybe some others should have inverter powered chillers (maybe reverse cycle) in the 10-ton range next year. Cost with phase converter will probably be 3x to 3.5x.
Is it better to have two 1-phase, one one-phase, or one more sophisticated 3-phase?