You really need to try that tyre size first, or a bike with a 650b x 42 on it. Whether you like the rolling-diameter feel.
If I was strictly on smooth paved surfaces I would only do it. Anything above groomed mild gravel and I would give it a miss.
For me a 650b x 42 feels borderline acceptable but only over smooth stuff. Over heavier stuff the tyre just feels too small.