What's the price difference? If there's a big difference, get the Linea and wait for Strada.
I have owned a Linea, a Linea with all the GB/5 upgrades but built on a Linea chassis, and a full fledged GB/5. The GB/5 is by far a better machine, easier to set up and easier to use. The pre-infusion is programmable in 0.1 sec increments for both infusion time and wait time after pre-infusion. The brew boiler temperature is also programmable from the front panel.
It is particularly a time saver when back-flushing. You do not have to stand there turning the pump on and off. It is programmed to go on and off thirty times while you could be doing something else.
Lots of other features.
The gicleur is now made of synthetic ruby that is much more stable than the old teflon orifices.