I dont know about splenda.
But ive got 100% pure caseinate at home. If someone where to switch it with drywall, i swear to god id be dead.
That is assuming that drinking large ammounts of drywall kills you.
But theres no way i could tell the difference.
Adding splenda might be a good idea. I thought it might go down easy in cottage cheese. But the ratio of CC to Caseinate would have to be prettty high.