The GS-4 is a nice looking product and can run nicely in ideal conditions. Beyond that don't waste your money on this moderately priced locomotive. I have Kato, Bachman and different Con-cor locos on my pike. The Kato's are perfect, the Bachman are mostly good and better with some tweaks, plus Bachman at least has a warranty. I have two ABA sets of Con-Cor PA-1's, two J-3A Hudson's which are consistent runners. The GS-4 purchased just over 2 years ago is the biggest disappointment of all, coupled with poor support from Con-Cor. The first thing to fail are the pins holding the drive rods to the drive wheels, it takes little to have them come out. These are impossible to reliably reconnect. The next failure is the gear connecting the motor gear to the drive wheel gears, the same gear that had previously failed on one of my Con-Cor PA-1s. If you disassemble the GS-4 locomotive it is nearly impossible to quarter the drive wheels. One year ago I ordered the parts from Con-Cor with no problem. The parts included a new drive wheel assembly and the aforementioned gear. I was able to get the locomotive running for a short period. During this short period I came to the conclusion that this locomotive was unable to negotiate the minimum 18" radius curves on my layout, hence back to the drawing boards and relaying tack to widen the curves. This had limited results in running the locomotive my other locomotives had no problems. This time I decided to reorder the same parts from Con-Cor only to be told they did not carry the parts only assemblies and they'd had this policy for 10 years, I even provided the invoice for the previous part order. I was told they only catered to model railroaders who wanted ready to run products then inferred that since I was able to disassemble a locomotive I was an old-timer and not in their target market. Con-Cor offered no solution to the problem only a litany of excuses. I special ordered 3 of the Con-Cors since several hobby shops told me they did not stock them because most people won't pay the price.
Since Con-Cor bought the tooling and states the GS-4 and S-2 Northern have the same tooling I foolishly bought a Con-Cor/Kato S-2 to compare the older model run with the newer. The older one was a good runner and was far better on my layout than the newer GS-4. Unfortunately in my curiosity to examine this locomotive further and compare the subtle differences to the newer model the drive wheels easily became unquartered. With extreme patience, time and repeated adjustments to quarter the drive wheels it could be a good locomotive.
At an MSRP of $299.99 the GS-4 is not cheap. N Scalers who consider purchasing this product would be well advised to read all the policies on Con-Cor's site. The policies are a real eye-opener of what Con-Cor can't do to back their products instead of what they can do. Unfortunately for this particular locomotive in this price range Con-Cor pretty much has an N scale exclusive.
I will not give up on getting these GS-4s to run so any feed back on how to properly quarter the drivers would be welcome.