Refugium with chaeto or bio-pellet reactor

[Aquattro]

My opinion is choose neither, until such time as you determine you need something. Keep in mind, that pic you posted was not the result of choosing a bio-pellet option. It's careful husbandry tied to lighting, flow, feeding, stocking,etc. You need to get it all right to get that tank. If you find a couple months in that you can't control nutrients, then look at options to deal with it. Carbon dosing is a good option.