Is state splitting the LR equivalent of LL nonterminal replication
It is indeed well-known that LR($k$) languages for $k&gt;0$ coincide with SLR($1$) languages, see e.g. M. Dennis Mickunas, Ronald L. Lancaster, and Victor B. Schneider, Transforming LR($k$) Grammars to LR(1), SLR(1), and (1,1) Bounded Right-Context Grammars, J. ACM 23(3):511--533, 1976, doi: 10.1145/321958.321972; it's not clear to me what EBNF syntax has to do with it: could you be more specific?



Edit: in answer to the more specific question regarding nullable nonterminals and LR($k$) vs. SLR($k$), the grammar with rules
$$S\to aAa\mid bAb\mid aBb\mid bBa, A\to a, B\to a$$
is LR(1) but neither SLR(1) nor LALR(1) and does not have any nullable nonterminal.

Another issue is that there is no "perfect" definition of LR($k$) for EBNF syntax---unless you convert to BNF in some specific way and ask the resulting grammar to be LR($k$); see Heilbrunner, Definition of ELR($k$) and ELL($k$) Grammars, Acta Inf. 11(2):169--176, 1979, doi: 10.1007/BF00264023.  The issue is with the reduction operation: how much of the stack should be reduced when reducing, say, $A\to a^\ast$?  Answering this question might require inspecting the stack contents, or adding special stack markers, or $\dots$, and is likely to restrict the class of accepted grammars below ELR($k$).

Finally, I do not know about SLR($k$) techniques for EBNF grammars; a survey on the subject of parsing for EBNF was recently written by Hemerik, Towards a Taxonomy for ECFG and RRPG Parsing, LATA'09, LNCS 5457:410--421, 2009, doi: 10.1007/978-3-642-00982-2_35.