I put CDI Flex Furlers on my Hunter 23 and 31 and enjoyed them. For the 34 and 36 I had Keys Rigging install the Harken ESP furlers. Having used both, I fault the CDI plastic luff groove for wearing over time as the sail is taken down and reinstalled, however, the overall durability and ease of installation is superior.
The Harken ESP is much smoother and easier in heavy winds on the bigger boats.
I'd go with the Harken on the 34.
I would caution against measuring the rig out of the water and then cutting or building a new forestay on that measurement. The boat WILL change shape afloat. That's why final rig tensions must be set in the water.