Compared to the rest of the costs involved, developer is a really small worry.

IMO the "effect" of the dilution you use, should be the primary driver. Typically for solvent type developers stock strength gives finer grain, more dilute gives more sharpness.

Which would you prefer?

Could you tell the difference?

Switching dilutions is about fine tuning, they are choices you can make in the future.

Any of the listed dilutions should work just fine for a first try even on an important roll.

http://ilfordphoto.com/Webfiles/2011427133131459.pdf