I've started keeping our eggshells and will see how it goes, but that will be for another batch.
As for this one, in an attempt to clear fully before bottling I've just mixed 5g of Bentonite in 100ml of warm water and mixed into the 23 litres with the degassing attachment for my drill, fingers crossed.
I have used bentonite as well. It's works very well, in my experience. But, does tend to strip the colour and some flavour as well. But, maybe I am imagining the flavour thing because of the loss of colour. I should say, this is when I have used it following fermentation.
Crushed eggshells, on the other hand, as well as being effectively cost free, tend to only affect acidity a little bit. At least that's what I have found. Though, I'll admit they don't clear the brew as efficiently as bentonite.
I'd be very interested to hear your own report on their use when you get round to using eggshells.