Hey, Caleb. We replaced most of the balsa in our SJ21's decks with CoreCell. It costs substantially more than scrim balsa; shipping for either costs so much the materials price difference pales.
Balsa is sometimes shipped rolled up, which may be cheaper. Balsa has more compression strength as a material (tho I'd be curious to know if that obtains post-install) but balsa's vertical shear and flexural properties are poor -- it will snap like a soda cracker. I found the CC to be fairly resistant to that, unless scored.
Both will drink a surprising amount of resin; you need to butter them well with neat mix before spreading the thickened resin, or you may end up with a starved bond. And any lightweight core material must still be isolated from water intrusion. CC will absorb a certain percentage of water, & it can delaminate from freeze/thaw just like balsa. The difference is it won't ROT. The balsa around our mast step looked like gravy. That trait alone steered me toward CC, & I am very happy with the result.
Our new-to-us '72 Ballad has some water intrusion problems around the mast partners, foredeck cleat
, and chainplates. Its deck is cored with 1" Divinycell. We drilled out a couple samples with a hole saw; even tho the wet plug was over 30% MC when removed, it had very high compressive strength. It dried out in about four days to 6% MC & now seems good as new. I've tried drying out saturated balsa, but the results were not as happy.
Either material is perfectly satisfactory if you keep the water out -- balsa has a slight performance edge in several categories. Let water in, and neither material is happy; balsa suffers most. FWIW, I put cast resin pads and/or phenolic plate under all high-load deck fittings, in place of core. Even if your bedding sealant fails, there's no risk of water intrusion. Little epoxy
collars are cute, but under winches
, travelers, deck cleats
, or around chainplate penetrations, gimme phenolic sheet running an inch or so oversize in all directions.
Yeah it's heavy -- so is a foam or balsa core full of water.