Mixed Receptive Expressive Disorder Success Stories

Our son will be 5 in 3 months and is Level 2 and non-verbal.. He has been in ABA minimum of 20 hours since diagnosis (now in 40) while also receiving 1 hr of OT and Speech weekly. We felt as though we were seeing progress, and now feel a complete plateau and regression. He was diagnosed with Mixed Receptive Express Disorder as well. Any success stories on talking after 5 with MRELD? Buddy works so very hard, but we're thinking the 40 hours has been too much. Any experience splitting ABA and a daycare / preschool and the benefits of doing so? Just looking for any encouragement at this point.