I have never driven an ERA, but the several i have seen are very handsome cars. So i can only talk about my SPF. I have seen any number of replicas lined up, and they all look just a tiny bit different, the FFR's a bit more so.
The parts you see in an SPF are very authentic, the dash, seats, etc. The IRS 8.8 rear with fully adjustable coil over suspension is superb, come with Bilstein's, my car has been upgraded to custom valved race Bilsteins and springs, by the way. Stock they come with Wilwood four piston calipers, stuff like that.
In my now over 48,000 miles in the past three years, my car has proven to be very reliable, and basically bulletproof. I don't hesitate to drive far far away, race on a track, and drive it home.
Never ever overheats, even in 100 degree traffic, has been down the quarter mile over 60 times, and on race courses for over 600 laps.
It is now up at my builder's, the Olthoff's, getting a race, full width roll bar, and sundry other "tweaks".
SPF dealer service is superb, they are trustworthy, and value their customers. There is a SPF owner's association, and private web association, the former with the Olthoff's setting up several race track driving schools each year, the latter giving about 50+ Email messages every day. If you want custom modifications to your car, even to full race prep, hardtops, and AC, your dealer can do that for you.
You are about to spend a significant amount of money, so you owe it yourself to sit in and drive one of each, so you can make the right decision for you.
These are fabulous cars to own and drive. I love the simple, robust practicality of my SPF.
There is something that Bob Oltoff, who raced and won in Cobras (and many other cars) has told me. That
oil quickly got on the inboard brakes of the real ones, and he never had any useful rear brakes for that reason. You might consider the ERA outboard brakes as an option.
If you don't mind, i will try to send you a picture of my SPF.
Best wishes, and join the Club!!!