Hello Henry: I can see that you get to the point.
The BDR runs around 2300 lbs. It can get up to 2500 depending on what you bolt into it. The suspension is of BMW vintage from the 95' 325 series. Ride height is fully adjustable and it runs 49% rear with a 302 block. The front sets up identical to the BMW with about an 1/8" toe-in to soften up the steering. It also has the sway bar to provide anti-dive. The rear also sets up identical with the exeption of 0 camber to keep the wheels flat on the road, stock calls for +1.5 or so. The car does sqaut under acceleration. This however, helps with the transfer of ponies to the pavement. No skid pad tests have been done at this time.
Completed performance numbers? Which car? I can tell you that the rear suspension does a good job with traction and the car road coarses extremly well. A 302 based engine will handle much better if you intend to race the car.The guys in Deep South Club race 5 or 6 of them regularly in Florida and they run very well against the other 20+ replicas of all makes. The suspension upgrade is an M3 package that include shocks, springs, 1/2 shafts, and brakes. This package requires 17" wheels to house the larger brakes.
A search will yield all the threads you can bare to read on the comparison of SPFs and ERAs. An ERA is probably one of the most sought after cars when authenticity is concerned, it is a very different car from the TKMs. With that said, I'll tell you why one might choose a BDR. As you have mentioned, the BDR is $12,000 less expensive than others. It is not less car, just less expensive. The car drives and handles like a dream. Both SPFs and BDRs are well made with attention to details and quality. A manufacturer is entitled to sell it's wares for whatever the market will bare. Sometimes a new product is introduced into a market that raises the bar by offering more value built into it's product. If price is not an issue for you, I would let first hand research make your decision for you. Look at all three cars and drive them. You'll probably find club members in your area to help out. Side by side, your choice will boil down to a personal preference.
Thanks,
Robert