Spec 44 wire?

Is Raychem Spec 44 wire a good alternative to Tefzel? From what I can gather, it has slightly thicker insulation (0.19mm versus 0.13mm), and two layers. Is there any drawbacks or limitations? Price-wise, it seems I can get 22AWG Spec 44 for around $0.95 AUD per m, versus 0.80 for TXL and $2.20 for Tefzel.

Yes, Spec 44 will work fine for engine or data harness use.

Yup, spec 44 is great! The dual wall, with a different colour on the inside can give a good indication if there is any abrasion damage too, as you'll see the second colour start to appear. Usually, with a fully sheathed harness this isnt much of a concern though, and spec55 / M22759/32 is thinner and lighter.