I don't think taking the revolver is a good idea, especially if it's not easily concealed: Relying on that so quickly and easily will make us look crazy and desperate, especially when under normal conditions we'd be able to danmaku with the best of them. And with only five shots, there's no WAY we're going to be able to muscle things back to normal with that.
Keep it in mind, but it would probably be best to keep it here to avoid discovery of our desperation/lack of power/ruthlessness and the temptation to use it or threaten to use it lightly.
As for which shikigami to bring along... that's difficult. We may actually not want to bring anyone. Ran with a missing arm would be a big red flag to people about our situation, and her presence elsewhere a signal to any prospective raiders that Mayohiga's defenses are lowered - I'm not sure how well Chen can defend the place on her own. As for bringing Chen, she might be a liability if she starts getting emotional or saying things we aren't looking to share, and I'm not sure how much she'd help in a fight at the scope we're likely to have to deal with.
Alternatively, we could just take both and leave those silly material possessions to the wolves for now. Once we're back up to power, it won't be that difficult to gap them back into our possession, will it? That, or just set up a way to keep the most important things safe while we deal with things. That in mind:
>How well-concealed is the revolver in our clothing, and does it impede our movement in any way/cause our clothing to look strange?
>Would Reimu's barriers be effective against the revolver's shots?
>How good is Chen in a fight, and at keeping a poker face during tense conversations?
>Do we know how Ran managed to limit the areas that Marisa could raid?
>If not, do we have any way to seal off feasible non-gap access to Mayohiga for a while?
We should ask Ran about how effective the last-line for-the-valuables defenses for Mayohiga are and how well they'd hold up without her here.
Also, I don't find going back for Alice a priority - Yuyuko is far more likely to help us, and right nearby to boot. Checking on the entrance to Hakugyokurou before leaving might be worthwhile, if nothing else.