The merits of a large ion heating fraction for theperformance of a tokamak reactor are investigated. The abilities of different ICRF heatingscenarios in providing significant ion heating are discussed. The 3Heminority scenario is found to be the most suitable scenario for a reactor.Simulations of ITER relevant scenarios suggest that the bulk ion heatingfraction is in the range of 70% for most of the heating phase. The benefitsof a large ion heating fraction are then discussed in the framework oftransport simulations. In particular, a large ion heating fraction is shownto lead to an improved control over the path to ignition. Finally, theimplications of a reduced size ITER are discussed. The steady stateperformance with 3He minority scenario is improved by 30% as comparedwith pure electron heating schemes.