Over potting in S/H?

[EmoryG]

Aloha All,

Am I right to think that plants would be much more tolerant of being "over potted" using s/h than more traditional (bark/sphagnum based) mixes?

I am wanting to repot a couple of recent purchases, Phrag. manzurii and Phrag. fischeri each with a leaf span of about 4". Of the containers I'm fond of using, the smallest are about the size of a 3" or 4" inch pot. Thoughts or concerns?

Side note: I have read that Phrag. fischeri likes it more alkaline and was thinking about mixing in oyster shells into the mix.

As far as my cultural considerations, I am in Hawaii with average humidity around 80%, pretty good ventilation and I water my phrags with rain water PH around 6.4. Typically I soak the plant in a solution of seaweed extract+inoculation before potting them in a mix of viastone, diatomite, small charcoal (roughly 6:2:1).

Thanks so much for the support.