Surface mounted is aboslutely not harder to assemble manually, it takes fraction of the time to lay 100 components on pasted pads before putting to oven and call it a day than to bend and cut pins of 100 through hole components, stuff them to the board, solder each of the pins (and make them look good too) and then clean the flux residue, more steps, more time...
Hand soldering the sufrace mounted parts may be slower if the tools are wrong, but good needlenose tweezers, right soldeling tip (throw away your conicals 🤣), solder wick (especially one with flux in it already) and correct flux will make things easy still. Drag methods are supreme, it takes much less time to solder up all the many tens of pins chips than the through hole ones.
On the sound cards I am making (and have made), soldering the few tens of through hole parts take longer than pick&placing the few hundred surface mounted parts.
I'm pretty sure all the lamentations that surface mounted parts are something to fear come from having the wrong tools and techniques. Lot of people do regular soldering without flux and them complain how things are so difficult but of course it is when you are missing a key ingredient of the process 🤣
Back on topic, that assembled board couple posts back does look good, at least on the top ~
As far as component size goes, technically the larger parts have lower tempcoeff which results in lower distortion and slightly lower excess noise due to more material for things to even out in but metal film parts are still much superior to carbon film ones regardless of their physical size (and these effects are all measurable aswell).