Kinetic Isotopic Effect in EAS
In general, deprotonation of a $\ce{C-D}$ bond would require more energy than that for $\ce{C-H}$ bond because the zero point vibrational energy of the bond is lowered. By referring to our harmonic oscillator zero point energy equation,
$E_0 = \frac{1}{2}h \nu$
where frequency is,
$\nu = \frac{1}{2 \pi} \sqrt{\frac{k}{\mu}}$
and the reduced mass ($\mu$) being,
$\mu = \frac{m_1m_2}{m_1 + m_2}$
we see that as the mass for either atom increases, the zero point energy decreases, therefore, the bond is relatively more stable than its lighter isotopologue. However, swapping out isotopes in a molecule does not change the potential energy surface for the reaction [1]
1.) Sulphonation
Changes in the rate determining step may arise from the type of sulfuric acid used. Since fuming sulfuric acid has a higher concentration of $\ce{SO3}$ (the electrophile) then more dilute forms of $\ce{H2SO4}$, the rate limiting step is no longer forming the bond between benzene and $\ce{SO3}$, rather, it is re-forming the aromatic ring through deprotonation. Ergo, if you did a KIE study with different concentrations of sulfuric acid, you may see that only fuming $\ce{H2SO4}$ shows significant values of $\frac{K_\ce{H}}{K_\ce{D}}$.
2.) Iodination
This article [2] studied the iodination of benzene with the source of iodine being generated through the &quot;oxidation of 0.5 g of $\ce{I2}$ in acetonitrile-tetraethylammonium perchlorate to 2.4 faradays/mol.&quot;

The article reported that the secondary kinetic isotope effect for $k_1$ and $k_{-1}$ is negligible, however, $\frac{K_\ce{H}}{K_\ce{D}} = 2.25$ for $k_2$.
Here is a thesis I found that discusses the iodination of aromatic rings [3]
The thesis, in short, suggests that whether the deprotonation is rate limiting has to do with the concentration of the reactants, along with the transition state of the molecule. The transition state is affected by the strength of the base, since a higher $\mathrm{p}K_\mathrm{b}$ may give a transition state where the hydrogen is partially bound to both the ring and the base, making this step in the reaction faster (therefore, not rate limiting). However, it did only investigate substituted aromatic rings, where substituents can play a significant role in the transition state, making the reaction with benzene a little less comparable.
3.) Nitration
This article reports no KIE observed in nitration of benzene [4].