If your priorities are music, I think you'll be much more satisfied with an 818 driving 5200SEs and using that for movies too, than a G65 driving a mix of the SEs with older subs/surrounds.

If your long-term goal is to have 800 series quality for music and movies, I think the advice to get a second hand 861v6 and then upgrade it as funds allow is the best option - that way you should equal quality for music as the 818 once you do the v8 upgrade and not compromise anywhere.

Maybe consider a dealer dem?

HC: 861v4/ID40/LPS, DSP5000, DSP5000VC, DSP3100, SW1600, HD621, Oppo BDP-105, Sony VPL-HW55ES
2-Channel: Oppo BDP-105, TEAC VRDS-7/Trichord Clock 3/PSU, 551, Quad 303, Harbeth Compact 7ES-3, Kimber cables, Russ Andrews mains and supports.
Previous Meridian: 5000C, 5200SL, 7200.2, 6000, 562V.2, 568.2mm, 800v4, 808.2i, 818v2/v3, 861v8, 502