Large (1.27 TB) Aperture 3.6 to Lightroom 5 Migration: Is it possible?

Hello

I hope someone can point me in the right direction.

I have a new (from apple refurb store) Mac Mini Quad Core 8 gb Ram with 1 TB fusion drive.

I have external drives with 5 TB of storage, 3 TB which is used.

My managed aperture library is on one of those drives and is 1.27TB total.

On using the Lightroom migration plug in, Aperture crashes. This is the process I followed.

1. Update all previews in Aperture to highest quality and full jpg size. This is so that all adjustments (cropping and minor exposure - nothing more) will be viewable in Lightroom as jpg imports (70% of the library is RAW files)

2. Tried migrating whole library. This crashes.

3. Split library into smaller libraries (date based e.g 2014 Q1, Q2, Q3, Q4 etc) in Aperture, and then import. This works, but creates huge 800gb libraries - and that was only 10% of my full library - This seems very large and is not a viable solution. How can the library be 1.27TB total, but when exporting it, 10% of it shows up us 800 gb?

My wish is to have maybe 5-10 small libraries in Lightroom of around 100 -200 gb each.

My questions...

Is this possible?

Should I forget about exporting previews to lightroom? Are the full size jpgs my problem?

Would working with referenced as opposed to managed files help things?

Any help is appreciated. Many thanks.