100 hours multi is a figure which several of the UK turboprop operators have asked for in the past. Just because they are not asking for it these days not mean that they don't want it. If you have jet aspirations as a first job though I think I would save the cash for a TR. I doubt MEP hours would help you much.
Besides, twins are more fun than singles and the Duchesses used by Riverside are a great aircraft. I have many hundreds of hours in the things and I still find them a pleasure to fly.
I would take the Riverside deal if it was my cash.