Personally I wouldn't attribute any value to the tech...

Personally I wouldn't attribute any value to the tech businesses. I haven't the foggiest how Mr Market sees them. It doesn't especially concern me either. The ability to produce earnings in the medium term does however, and, as noted, there's little to evidence to suggest that they will produce any, let alone enough to justify the associated costs of capital and the attendant opportunity costs. Perhaps a negative value would be more appropriate.

Currency adjusted, NTA is effectively at parity with the price now.

Precision engineering revenue didn't grow last year. Yes, it grew seemingly quickly over a 4 year period (the 46% cagr you refer to), but what suggests it's suddenly going to continue? Comparing precision engineering confirmed orders, in the 2012 annual report they specify $22.2m as confirmed (page 9), whereas in this year's it's $6.5 confirmed (page 11). Does this imply your darling is going backwards?