To be honest I'm not sure if it's the same issues exactly.

I am beginning to suspect there is an upper size limit on what this software can work-with. The files which do succeed are layered psb's, and are upwards of 5 Gigs.

The owner's manual gives some advice regarding preferences for large panos, which seems counter intuitive in some ways, the way I interpret it they are making recommendations such as reducing cache-size for example, asa workaround for smaller computers.

In my case I am running what is likely near the top-end of technology and still experiencing problems.

That being said, I seem to have less crashes if I completely restart my computer after every pano.

In the end, there may be some of my preferences which are not yet optimized, but so-far have been unable to get definitive + comprehensive answers to the question.

At this point I just want some accurate information, perhaps this software is not capable of delivering what I'm asking.

My selection is psd/psb because I want all the layers - in addition to the rendered/flattened layer.
I am setting the resolution at 300 dpi - which is the same as my original files.

Yes you are correct regarding the size and number of files I am stitching, though I did originally overstate the size slightly in error, after double checking I see they are closer to 225 megabytes each. 11 is the maximum I try to stitch, the orientation is identical - that is they are all vertical 'plates'

Interestingly, the crashes usually happen at the same point in the stitch, at the start of the Smartblend stage of processing.

I am prepared to set prefs to make the process slower if that would help, but my ambition is for best quality and hopefully more stability/less crashes, it's a pain when you can't trust a software to leave it alone.

I am on the latest Intel Mac Pro running Leopard (10.5.6) with 10 Gig of Ram.

Hi.
Achieving such size on the mac platform should still work with 32bits version, but it will be easier with the 64bits release. This one should come out soon ( within 2 weeks at most ).
Now, just a notice about smartblend : this is a really heavy algorithm and it's always complicated to apply it on big panorama. Harlem-13-gigapixels was rendered in multiband and this will work. Smartblend on big panorama needs extra attention on harddrive. Some customers uses dedicated Raid-10 drives to achieve the rendering with smartblend.