I'm 5'8". It is more dependent on your weight (I'm 74kg) and boot size, plus a lot of modern powder boards have got shorter but wider to maintain area and accommodate big feet (although dedicated split designs tend to buck this trend to fit in the skin track). Then with directional boards like mine the tail is effectively cut-off so you get a longer running edge and similar effective surface area but the length is shorter. Plus some (older?) boards seem to be measured along the base vs length overall.
Normally you size up for deep snow, so for you traditionally 159-161 depending on weight - my solid is 154 but wider, split is 159 and narrower. It feels a tiny bit big, but it's also highly directional.
If the Amplid freequencer includes skins (I would defo check) it's mega deal, worth a punt just to get started. The 153 would be on the small side but - if your feet fit - probably preferable to a 166 unless you're guaranteed snorkelling conditions (specs on
amplid.com say 153<80kg<166). After a 156 custom it shouldn't feel much different, a touch easier to turn but not tiny. Amplid also have a direct outlet which always has good deals and occasional great ones. The Amplid skins are made
The Arbor boards are not such great deals but they have mid sizes and are well reviewed. The Satori is more of a modern wider board so probably sizing slightly shorter than your custom would be fine, but again check the specs.
Once you factor in pucks, bindings, skins, poles, avvy gear it does get quite spenny mind... but you can always upgrade the board when the sales come round next year. Second hand splits in half decent condition sell for >£250 on ebay. I think there was a big split boom due to covid so good end-of-line deals now seem a lot more common than pre-covid.
I feel like that Sommelier 166 has got Lager's name all over it...
https://www.youtube.com/watch?v=D_mEKnSwryE&t=156s