I am in Sao Paulo, humidity is 80%, after a few hours with a dehumidifier I can get to 60% woohoo, I am using the small premiers for now. I was afraid that the humidity was causing my 70-80% bars to be too viscous and thought that roasting nibs, instead of cacao, would help me maintain more butter in the nibs. I will weight before and after roasting, then after proofing and see how this changes things. Thanks everyone. 

I would say that rheology depends on MANY factors, your PSD being just one of them.  How much moistuer you have post roast in your nibs, how much you can drive off in your conche, how effectively you emulsify, your other ingredients, etc all play vital roles in rheology.

The lining should be ok - it's been used less than 200 hours total so far. I do use standard white table sugar though, so a two-roll prefiner should be my next purchase

That then becomes a little more complicated.  The lining on your macintyre will abrade away over time, resuting larger particle sizes the more you use it.  You can have it relined, but the specifics of your PSD will be pretty related to the health of your lining currently.  Also, are you using crystalline sugar (ie standard table sugar)? The starting size of your crystals also has an impact of how they break.  Most 'table' sugar type sugar is int he 600-3000 um starting particle size range, and can benefit from going through a 2 roll prerefiner to reduce the amount of fines they can generate.

I currently put the nibs straight into the MacIntyre, and put whole sugar in a bit afterwards. I get to ~15 microns (measured with a micrometer) in around 22 hours.

Next would be getting a grinder, then a 3-roll refiner. It's been put off because of lack of capital.

Depends entirely on what distriubution you get.  If you end up with a distribution that tight, but very small particle size - then no... as with many things, the devil's in the details here.  Most prerefining configurations will result in less super fines, which will give you a lower viscosity (less thick) chocolate.  Some configurations won't.  How do you plan to prerefine and how are you currently refining?  Sorry if youp'd already noted that...

That should lead to more fluid chocolate, right?

Pre-refining will likely give you a tighter PSD.

If I was going to go with a belt feed, I'd probably get one of those toasters / pizza ovens with a conveyor belt. I would use the searzall manually to find out if nib roasting helps improve my chocolate's quality - unfortunately there doesn't seem to be a consensus on that question

To get back to Arcelia's motivation though - besides adding cocoa butter, my biggest gain for fluidity has been getting a micrometer, which got me to realize I was under-refining. I did have some sticky, over-refined chocolate (hard with a premier but possible with a MacIntyre style conche) and that got me thinking about particle size distribution. Maybe if I pre-refined I'd have a more consistent size distribution, as chocolate spends less time in the refiner.

Arcelia, I'd love to hear about your setup and what other avenues you've tried. Is your grinding area very humid?

Interseting - i've never seen a searzall - now i want one.  The heart wants what the heart wants.

It'd probably work.  I'd urge you to set it at a fixed height above and below the beans, and belt feed the beans through.  You'll need to do some trialing and error attempts to identify the correct height and residence time of the beans to get the moisture to flash out w/o roasting the beans.  But i suspect it's doable.

How hot should we go to get the shell adequately dried off?

On the more extreme end of accessible short-time, high-temperature options are propane torches, maybe with attachments like the Searzall. I'd love to know if anyone has tried this.

It would have no impact on reheology.

The best way to remove the shell is to 'pre roast' or micronize the whole beans to faciliate some moisture removal from the shell to reduce it's adhesion to the nib, and result in it's easier separation from the nib.

Hi there, is anyone cracking unroasted beans, winnowing, then roasting the nibs? I am curious whether this would create a less viscous chocolate since more of the cocoa butter would in the nibs and not absorbed by the husk. Also, is there a trick to cracking unroasted beans. Thanks!