The lawyers at V&E would tell you that there are so many economic factors about YieldCos that mirror MLPs, they are a natural extension to the space. Some even argue that YieldCos diminish the importance of the recently re-introduced MLP Parity Act. As of today, there are less than 10 YieldCos trading on public exchanges as compared to 127 MLPs.
On the surface, YieldCos and MLPs may share similar characteristics, but the small nuances make them different enough to where each should have its own set of valuation techniques. In the same way that a royalty trust has a finite life, NOLs for YieldCos do too. A royalty trust investor would not use the same valuation metrics as an MLP investor does, and neither should a YieldCo investor.