Let's review what I think we know. (BTW, nothing I say below applies to lunar returns. The rules are different.)
- Regarding location for SSRs, I am CERTAIN that an SSR's original angles persist both in the sense of its angularities describing the year AND in terms of transits. Transits to "where it occurred" SSR angles operate vividly throughout the year.
- Relocated SSR angles (which includes coming home from a vacation) are, at best, only weakly present. This includes both angular planet effects and transits to them. As time goes on, I lean increasingly toward thinking that they don't exist at all. (One can at least act as if this were so in most cases.) This year, since my SSR angles aren't far from their relocated-to-home positions, I've been able to study the small differences, where fast planet transits across the two SSR angle sets occur a couple of days apart. So far, it seems that the transits across original SSR angles are solidly present and those across relocated-to-home SSR angles don't exist at all. (But, again: They may exist but very weakly.)
- Mundane aspects are equal in every respect to ecliptical aspects. There is no difference between them in a return chart at all. Use them interchangeably. (This includes transit-to-transit, transit-to-natal, and natal-to-natal.)
I am inclined to think they persist because, in general, when one looks at a large collection of famous people without paying attention to where they live at different points in their lives, the close natal mundane aspects seem to show interchangeably with the close natal ecliptical aspects. Also, individual cases seem to show their continued importance. - However, I allow that maybe this is because one develops habits and other behavior patterns when initially living under a mundane aspect at one location, and these ingrained behaviors continue when one leaves the original location. So far, the evidence weighs slightly against this view, but it's a possibility I keep in mind. (If valid, it probably doesn't have any significance for the short-term one-year solar returns.)
I am inclined to think they at least weaken because one way to distinguish the quality of two locations for a person is to contrast mundane aspects at one location with those at another. Even if the close mundane aspect in one location is an ecliptical aspect in the other, the orb difference seems to make a difference.
It's possible (more than possible) that mundane aspects are more prone to manifest as external events more than as character. (Character traits would then come from reaction to the overt events, rather than have a sense of being innate.) This is consistent with how mundane characteristics seem to operate and matches some good examples. - This is consistent with the fact that there is no evident difference between mundane and ecliptical aspects in return charts (which are all about events) but have a slightly different feel in natal charts. This remains an open question and needs more attention over time.
As an example: Mundane aspects I have at birthplace:
Mars-Neptune square 0°07' [but 2°25' ecliptic anyway]
Mundane aspects I have at residence for last 47 years]:
Uranus-Neptune square 0°11' [but 2°00' ecliptic anyway]
Jupiter-Neptune square 0°33' [but 2°16' ecliptic anyway]
Mercury-Saturn conjunction 1°36' [but 2°24' ecliptic anyway]
Sun-Mars square 4°47' [but 6°28' ecliptic anyway]
I would expect all of these to manifest about the same - all but one orb pair is in the same class - but the contrast of the two lists for experiences in the two locations is dramatic. It's not unreasonable to say that, while having all these traits throughout my life, my life was significantly more Mars-Neptune in Indiana and more Jupiter-Neptune, Uranus-Neptune, and Sun-Mars in California. (Mercury-Saturn seems present in both places because it's similar to Virgo Sun in key respects, and my increased rational thought could have increased in California just because it normally matures around 25 yo. Nonetheless, it's still more descriptive of me here than in Indiana.) The mix is pretty descriptive.
Another example is my wife. She has no mundane aspects at birthplace (none that are as close as their ecliptical equivalents). For LA she gains two Class 1 mundane aspects. Her natal Mars-Uranus conjunction (Class 1 and angular at birth) gets a lot closer, 1°28'in mundo. More distinctively, her ~5° Mars-Saturn opposition at birth moves to 3°37' (Class 2 to Class 1 shift) in LA. This city hasn't been good to her in some respects. (But she has this in Northern California, too, which generally worked better for her: It seems to show some toughness she developed in her adulthood on the West Coast.) In Homer, Alaska where she lived twice and loved it, she picked up mundane Sun square Venus-Neptune, plus her Mars-Uranus conjunction reached 0°00'! (Among other things.) These show very well.
My only point in this is that there is a difference in the two in a natal chart - the relocated mundane aspects seem to show more the experiences of the location. They may (either directly or secondary to adapting to the changing events) remold the character.
Now, back to SSRs.