I've not noticed it on my end and while the available tasks are a bit below average on the server, https://boinc.bakerlab.org/rosetta/server_status.php shows 2026 unsent Rosetta tasks and 13234 Rosetta Mini tasks so you shouldn't be having an issue.

My test machines are supposed to arrive tomorrow and I'll split them evenly between WCG and R@h so in a few days should have a good baseline for what is to be expected between the two for determining a fair RAC equivalent.  But in the meantime, you might consider throwing some power at WCG as a hedge.  The R@h project we're tending to be in the 15% work performed range (we solved 13% of the work units overall yesterday), whereas if we did a comparable amount of work at WCG (roughly 5M RAC) we'd be around 3-5% (although right now we're less than 1%).  That is to say the WCG project can handle the influx much better than R@h can.