It depends a lot on the variety. I would aim for a minimum of 150g/l fruit, 200g if you can, and more of the rhubarb. It doesn't come through as well. Also, rhubarb's tartness is from malic acid, not lactic, so it may bring more sourness without as much of the fruit flavour.
Strawberries have a lot of aroma compounds in the sugars so the flavour will fade as the sugars are consumed. It is bloody great after 1 or 2 weeks, but can't stand up to the lasting flavour of raspberries (3 years) or cherry (10+).