A comparative analysis of wave profile modification effects in Raman free-electron lasers is presented. The analysis is based on a 3D theoretical model that is valid in both Raman and Compton regimes. We study two companion effects, the optical guiding and the excitation of space-charge waves with transverse field components. Both effects are compared through exemplary parameters based on previous free-electron laser experiments. We conclude that transverse field profile modification due to space-charge waves may be significant in comparison to the optical guiding effect.