There is no risk. Only that batteries will perform, most likely, worst than when you buy them from a matcher.
A matcher will determine which cells are good and which are bad. Then take all good sells and give you a pack that all 4,5 or 6 cells are more or less the same. That means when you run them, all cells to dump at same time hence giving you full power for the rest time.
Actually, most likely those cells (unmatched) might last longer since they haven't "abused" by a matcher
I hope I explained it sufficiently
By the way, is there a way to determine on the IB cells if they WC or juct SHV?