Looking to get started on 2m EME and have narrowed down to a 4x17 element long boom yagi array. Station specs suggest four 16 Element long boom yagi's computer optimized for extreme weak signals but I'm finding 17-element designs with better F/B ratios. Power budget is 1kW SSPA into 0.5-0.8 dB NF preamplifier at the antenna input point. Question: Is the extra element worth the mechanical complexity, and what's the minimum sky temperature threshold I should target for decent copy?

For successful EME contact on 144MHz, sky noise in direction of the Moon has to be less or equal 500°K. Should I expect reasonable results with this configuration using JT65/Q65?

Computer technology and specialised data modes have considerably reduced the requirements on equipment, bringing Moonbounce within reach of many radio amateurs. Your 4x17el setup with 1kW should work fine for JT65. QRA64 activity on 2-meter EME is becoming significant, especially on weekends, decoding signals down to about –28 dB signal-to-noise.

I'm running 4x16el M2 antennas with similar power and getting good results. The 17th element gives maybe 0.3dB gain but adds wind loading. 144MHz moonbounce sits on a knife edge – it works, but only just. Focus on getting excellent coax and phasing harnesses first - that's where most people lose dB.

Q65 weak-signal performance is the best among all WSJT-X modes on paths with Doppler spread, particularly effective for EME on VHF and higher bands. I'd suggest learning both JT65 and Q65 - Q65 offers wide variety of sequence lengths, and QSOs are possible at signal levels 10 to 15 dB below those required for CW.