What is the uHz-rotator algorithm?
From the (limited) description the uHz rotator algorithm sounds like one of the phase-weighted averages from this site, but it's not an algorithm I am familiar with.

The Cramér–Rao lower bound$^1$ for estimating the frequency of sinusoid with amplitude $A$ in white noise with variance $\sigma^2$ is given by:

$$
\mathrm{var}(\hat{f}) \ge \frac{12}{(2\pi)^2\eta N(N^2-1)}
$$

where $N$ is the number of samples and $\eta = A^2/(2\sigma^2)$ (taken from Kay's Fundamentals of Statistical Signal Processing, Estimation Theory equation 3.41).  

So, assuming $A =1$, $\sigma^2 = 0.1$, and assuming that frequency accuracy can exceed 8 significant digits means that $\mathrm{var}(\hat{f}) &lt; (10^{-8})^2$ we get:
$$
\begin{array}
\ (10^{-8})^2 &amp;\ge&amp; \frac{12}{(2\pi)^2 5 N(N^2-1)}\\
\frac{20}{12} \pi^2 \times 10^{-16} &amp;\ge&amp; \frac{1}{N(N^2-1)}\\
N(N^2-1) &amp;\ge&amp; 6.079271 \times 10^{14}\\
N &amp;\ge&amp;  84713
\end{array}
$$

This means that your data length would need to be 84713 samples to achieve this accuracy.

For different values of $\sigma^2$ see the following table.

$$
\begin{array}
\ \sigma^2 &amp; \eta &amp; 10\log_{10}(\eta) &amp; N\\
\\
0.1&amp;    5.\ \ &amp;    6.9897\ \ &amp;    84714.\\  
\\
    0.01&amp;    50.\ \ &amp;    16.9897\ \ &amp;    39321.\\  
\\
    0.001&amp;    500.\ \ &amp;    26.9897\ \ &amp;    18252.\\  
\\
    0.0001&amp;    5000.\ \ &amp;    36.9897\ \ &amp;    8472.\\  
\end{array}
$$

PS: I have emailed the author of that web-site and asked for their comment. Let's see if they respond.



$^1$ The Cramér–Rao lower bound is the lowest achievable variance of an unbiased estimator.