I tried different 2nd trick leads for this hand (S4, D trump, 1st trick won w/ 9D):
lead QD: (3,734 / 40,687 / 26,156) [2 pts / 1 pt / euchred] EV = -0.059
lead 10H: (2,375, 43,075 / 25,127) EV = -0.034
lead QD: (3,807 / 40,674 / 26,402) EV = -0.064
lead QH: (2,449 / 42,974 / 25,460) EV = -0.043
lead QH (2,285 / 42,858 / 25,337)
lead 10H: (2,283 / 42,870 / 25,327)
just 28 pts separate these last two, or 0.0004 of EV
It seems drawing trump leads to more sweeps but also more euchres, and since the latter is 3 times worse than the former is good, it's better to just lead the off-suit.
In all these hands the decision got to S4 about 70% of the time, and S4 won the first trick with the 10D about 50% of those times. I would suggest leading your worst card, but I can't guarantee my program is playing the hands optimally.
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I tried different 2nd trick leads for this hand (S4, D trump, 1st trick won w/ 9D):
lead 10D: (4,100 / 41,825 / 24,524) [2 pts / 1 pt / euchred] EV = +0.014
lead 10H: (2,845 / 44,709 / 22,895) EV = +0.065
lead AD: (4,174 / 40,494 / 25,736) EV = -0.037
lead 10H: (2,845 / 44,709 / 22,895) EV = +0.061
I come to the same conclusion as above. Slightly better overall outcome due to having a slightly better hand.
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Given these results I thought I'd also try:
Same set up as above; I replaced H with C to avoid having a better bid in H. 9S turned, about 29,000 situations tested each scenario.
lead 10D: (4,259 / 43,739 / 25,564) EV = +0.015
lead 10C: (3,262 / 48,560 / 21,740) EV = +0.158
lead jH: (4,536 / 43,520 / 25,812) EV = +0.013
lead 10C: (3,136 / 48,838 / 21,894) EV = +0.153
Here there seems to be even a stronger case for playing an off-suit. My conclusion would be that it is only better to draw trump if you have the boss card in an off-suit. At least for hands of this strength.