I don't think you are crazy....unless you sell the CZ5 to get a CZ70 Pro !
I have several analog units and a CZ70 Pro. The Pro does have a few advantages such as the notching feature, back light and the 4th tone compared to the CZ5.
I just like the analog units better because you can fine tune the sensitivity, where as the digitals are set to an incremental range and you increase/decrease. Also, I feel the analogs react to a target a bit quicker and the VCO pin point feature is better on them.
For what some of the nice used CZ70 Pro's are going for these days on the forums, it's not a bad idea to pick one up. The one I got is really nice, super deep (can run high sensitivity without any falsing using the 10.5 inch coil), and ID's spot on. I got a good one. Was like new. Only downfall is I don't think FT will service them any longer.
You can always sell it for pretty much what you will pay for it. Used ones go pretty quickly when they come up for sale if the price is right. $325-$375 range is a good deal in my opinion.
It's always nice to have a good back up CZ. Even in this day and age.