I've been running a decent 2M tropo setup for years (single 17-element Yagi, IC-9700, 200W) and want to try EME. JT65 with about 80W using a 12-15 dBi Yagi works well for EME according to what I've read, but I'm seeing conflicting info on digital modes.

Current setup: horizontal 17-el at 15m, can't elevate but moon passes 10-20° above horizon regularly. Single Yagi pointing to horizon allows EME contacts till Moon is 15-18 degrees above horizon. Should I stick with JT65B or move to Q65? What's the real-world minimum for first contact attempts?

Q65 is particularly effective for EME on VHF and higher bands and is becoming the preferred mode. Q65 may replace JT65 for EME use over time. Your setup should work fine - I've made contacts with similar power levels using Q65-60C on 144.170. The key is finding a big station to work with initially.

Start with Q65-60C on 144.170 MHz. For 2 meters, the standard is 60-C sequence and sub-mode C. Your antenna gain and power are adequate, especially if you schedule with stations running kilowatt and large arrays. The averaging capability in Q65 makes a huge difference for weaker stations.

Don't forget the low-noise preamp - critical for EME! Install a low noise preamplifier with 0.5-0.8 dB NF at the antenna input point. Also use quality coax like LMR-400. Your 17-element should give you around 14-15 dBi gain which puts you in the game, especially with digital modes doing the heavy lifting.