What would Capa say about S-Chess?  Not bad, but the extra mechanism in the drop is unnecessary by enlarging the board. Beyond Capa's thought, are Hawk(bn) and Elephant(rn) second fiddle?  If not, why not rather pre-situate Hawk and Elephant and then serial-drop the Queen and later some one other piece, to keep the desparate 8x8 size? Start these things and there are hundreds of S-Chess subvariants at large.  A designer can think of one subvariant a minute or more, and an incidental programmer can never keep up since it takes him an hour minimum to alter/add the right code to fit.  So let's stay with the gm S-Chess design specifics, not to embarrass programming-savvy designers.  S-Chess is intended anyway not as some Next Chess, but as a diversion and decoy, obviously intended to be picked apart.  Seirawan knows it is not going anywhere but fun to analyze between rounds.
Http://www.chessbase.com/newsdetail.asp?newsid=7638.
Ergo two exhibits: (I) Specifically here, for example, Knight exits b1-c3 and the next turn or two Elephant dropped (bulkily) to b1 guards that very Horse. The 'b-1' White Elephant -- pun intended -- out of nowhere cannot figure in a castling maneuvre of course.  To castle Queenside, White Elephant in fact now has to clear out pronto.  Thus Elephant can exit the same way original Knight did, or Elephant just wait until the b-file Pawn two-steps.  Then Elephant can go Rook-style like b1-b3.  Scads of fun but does it feel really justifiably Chess-like-deep, natural and inspiring?  
(II) In S-Chess, on little 64 squares player, without having promoted a Pawn, can have four Knight-steps attacking a given square from behind at once, for instance, 'd4' well-guarded by all of conforming Knight on c2, Knight on f3, Knight-leg Elephant e2, Knight-leg Hawk b3.  Demonstrating over-the-hill soon-400-year-old 'RN' and 'BN' ex Carrera overkill to the spry space 'd4' nigh.  Unaesthetic.