Does providing textbook solutions benefit the student?
Why do you need "research in peer reviewed journals" for something you can easily figure out experimentally yourself in a couple of semesters using exactly the setup you are interested in? The students also provide you with a lot of feedback themselves if you bother to ask them and to listen to the answers. The typical answer to this question (coming from those who have no trouble with the subject) is something along the lines "Yes, I do need to see written solutions to exercises to have a sample of exemplary argument construction and mathematical writing I can follow". I buy this 100% and do not care in the slightest what the modern education theories say after that.