The ELR is a great car and I love mine, but keep in mind the only approx. 3000 were made and it will likely be near impossible to get certain parts in the not to distant future. This is less of an issue with the volt due to production numbers.
The drivetrain and voltec systems are shared with G1 with some tweaks and is rock solid, probably more so then G2; however, all the sheet metal, headlights, tailights, trim, and certain interior pieces are not shared with other models. A minor accident could end up totaling an ELR because of exterior parts availability.So if might behoove you to buy two of them, or look for a wrecked one for parts. But isn't the drivetrain essentially the same as the G1 volt other than some software tweaks to get a little more performance and a larger SOC?