Both games would be DAS. On the H17 game I have used a 1to8 but on the S17 game I pretty much use 1to6 just to keep from attracting too much attention. Thanks Don for chiming in since this is truly your area of expertise.
the one where the casino has the best tolerance. These types of discussions have zero to do with your long term profitability...they are merely theoretical in nature (I hope you realize this). You will make the large majority of your lifetime EV at the casinos with typically average games that let you play without any heat or other issues. (Those casinos also usually make the most money because they don't sweat the action and don't scare away or back off otherwise good customers by mistake).
From CVCX for Heads-up, HiLo Full Indexes, DD, DAS:
S17, deal 1.21/2 decks, spread 1:6, SCORE 48.08
H17, deal 1.40/2 decks, spread 1:8, SCORE 73.28
Thus, the H17 game is much better, partly due to the wider spread. If we limit the H17 game to a 1:6 spread also, then the SCORE falls to 58.70: still better than the S17 game, due to the better penetration.
Answering something like this is always tricky. Not only is the exact penetration to the card important, but also spread, number of players at the table, and number of indices used.
So, for example, if you do the same study with a somewhat more realistic three players at the table and just the I18 (or, rather, Sweet 16, without ten-splitting), the comparison, as I mentioned, is much, much closer: 43.20 to 46.56.