The big difference would be finding a VX. CRX HF's that are in half decent shape and not modified are hard enough, but a VX? Good luck. Because they are newer and have a back seat, the VX's also cost more. From what I could find in CA when I was looking for my HF, a clean VX will be well over $3000, a clean HF is between 2-3K.
the HF is older tecnoligy, it has less power and over comes acceleration by being lighter and I would assume slightly more aerodinamic, it also puts out peek toruqe at slightly lower RPM and is thus geared higher to keep the engine running slower in top gear.
The VX uses more advanced tecnoligy to produce more peek horse power at high revs, while keeping the low rev power band more practical for daily driving, alowing it to be a larger heavier car with a back seat, I've driven both my 1985 crx hf, and 1992 civic vx both with slightly more weight then they were designed to carry, and the vx's extra power is nice if you have 5 adults in the car and need to get on the freeway, of course it has it's draw backs, like that extra power needs to be kept on a leash or your mileage goes down quickly, the vx has expsensive part like o2 sensor that seem to be coming to the end of their life cycle.
the only thing that would keep me from wanting to get another CRX HF is that they only used 2 piston rings insted of 3 (or so I hear) and that low compression, and burning oil is a commen problem after 200,000 miles, this is not a commen problem I've heard about in a VX.
I'd say they are both awesome for FE...
It depends on how much you value a back seat. The hf is getting up there in years, but if you could find a nice one, they are great cars. very tall gearing!
So far I'd agree that the VX is tempermental. It does have a lot of power and torque for an economy car. I have had one for three weeks and am ironing out all of the problems. well it works fine, gets me from point a-b, but I still haven't got the lean burn to run as smoothly as i would like.