Hi IanH
You can definitely use the Delta 105 if that is more in line with the budget.
The cost variance is in the material difference and where they are made (labor costs).
Delta 105 - composite mount, composite cage. Mount is made in Asia.
Delta Sonic - carbon fiber cage, stainless steel mount which is individually bent and made in the USA.
If you go with the Delta 105, you will notice a bit more movement in the mount and the Xenon cage won't grip as tight as the Gorilla, but should hold a decent amount of bottles.
As far as naming, we called our Cervelo-specific carriers 'Sonic' - so we have dual Sonic carriers and single Sonic carriers. Couple to a few years after they were developed other bike manufacturers starting using same mounting methods. So although the name meaning is no longer valid, we kept it as it goes with our aerospace background!
Candice Turner
CEO
XLAB - Aerodynamic Triathlon Accessories
Dawn to Dusk - Off-road Specific Storage Accessories
http://www.XLAB-USA.com http://www.dawntodusk.bike