Thanks for your suggestions.

@Joe: I did consider Seirawan-style gating for the Lion, but decided against it because it introduces yet another 'weirdness' from the POV of the naive Chess player. Your idea with the extra square is interesting, but it is not logically different from allowing a piece drop inside the 'Palace' (to speak in Xiangqi terms) and starting with the Lion in hand. (Well, OK, the rule that you can kamikaze-capture the Lion there makes it different, but in practice no one would be so foolish to allow his Lion to be taken by another piece, so that is a pretty moot point.) And if a resticted drop is going to be used to introduce the Lion, I would prefer restricting the drop to the back-rank.

I am in doubt whether the rule complication needed for introducing the Lion into the game is worth it, just to have a more aestethically pleasing array, with a uniform Pawn rank. Leaving out the third-rank Pawn give you a Rook on an half-open file immediately, which strategically would be a very large departure from FIDE. Especially in a mirror-symmetric setup, where the one to last moves his Knight away gets it soft-pinned on the Rook in a very nasty way. Indeed centro-symmetric setups appeal to me more, but on the down-side, they are a larger departure from FIDE. And the half-open Rook file then would point directly to the King side, making castling to either side unattractive.

@Greg: Using a non-8x8 board is a real discouragement for people to play it over the board. Here in the Netherlands 10x10 boards are common, because more people play interntational draughts here than Chess. So 8x8 and 10x10 boards are typically sold back-to-back. But in the rest of the World the situation is pretty dismal. So if possible at all, I would like to keep it 8x8.

@Antoine: I thought some more about the end-game problem, and it seems a real problem. Even without tablebases it is easy to see that KLPKL is much more drawish than FIDE KPK. Kings are safe from being driven to mate by the enemy Lion (and even from perpetual check) when they take shelter next to their own Lion, even in the middle of the board. And when the defending side parks his Lion next to the Pawn file in front of the Pawn, ready to igui it away when it comes in range, protected by its King, there is just no way to chase it away.

So it seems a bit of tweaking of the Lion-capture rules is needed. First I thought (inspired by Antoine's remark) of allowing distant LxL capture when only Pawns and Lions are left. But then I got an idea that accomplishes nearly the same in a natural way:

Forbid distant Lion x Lion capture during the entire game only if pseudo-legal recapture BY A NON-KING is possible. When you are then down to King + Lion, there is no way you can protect your Lion from being traded anymore. This will be enough to make advantages that are winning in FIDE also winning with a pair of Lions added. During the middle-game you would not normally want to use your King as only protector of your Lion anyway, so there seems little danger that this rule modification would lead to early Lion trading.