It's totally possible, perhaps even likely, that Brian was initially more willing to go in an Americana and/or bittersweet angsty direction at first (look at those early songs, the name "Dumb Angel," not shutting down Van's "stick it to the Brits" ideas) but by late October at the latest, with the Holmes cover delivered and sudden inclusion of comedy sketches in the sessions, I think Brian was on a humor kick and anything he perceived as a hindrance to that design was suddenly on the chopping block.
Fascinating and thought provoking conversation as always, but I take strong issue with this statement. I think the session tapes themselves for the album as a whole and for heroes, through at least February 1967, strongly suggest that Brian believed the Americana theme, the bittersweet, angsty direction, and his interest in humor were entirely compatible and could be combined into an album that combined all three seamlessly. Heroes the single combines all three, and the album sessions as a whole combine all three. What you see as evidence for Brian turning away from serious themes and towards humor (the newly uncovered Windchimes experiments, the Rock with me Henry Wonderful, the psychedelic skits), I see as evidence that Brian believed these things could be successfully combined within one project, but wasn't exactly sure where the line should be.
I think your arguments about the turn to Smiley when it happens later in 1967 are more compelling. But there, too, I think there is an alternative explanation that needs to be considered, which is that Brian's primary motivation was not about the content of Smiley Smile, but rather the *way* in which it would be recorded. I would posit that what Brian wanted, above all, was to hold sessions for Smile's replacement in a chill, relaxed, atmosphere, at home, without sessions musicians, and with all the members of the band involved. And I would further suggest that Smiley brought out the humor side of the project because Brian felt it was most compatible with the atmosphere and approach he wanted to bring to the process of making music at that time, rather than that Brian turned to a chiller, more laid-back, and less studio-intensive process *because* he cared more about the humor side of the project than its other aspects. I agree that the historical record clearly demonstrates that Brian valued the humor element of the project very highly, but do not agree at all that the historical record clearly demonstrates that he valued it *more* than the project's more serious side, which was clearly also of immense importance to Brian, as evidenced by the tremendous care he took in arranging and recording songs like Surf's Up and Wonderful in the first place.

















). But lighter variants of H&V from the work in Jan-Feb could be what stitches things together across the two sides of the LP. A musical comedy/overture snippet could provide the transition into the innocence section culminating in Surf's Up.





