I have also received a quote for a Danfoss at about 2/3rds the price.
I would stick with the compressor from Trane. Since there are multiple compressors in tandem on the same circuit, there is an orifice plate that goes in the suction line of the compressor. It is critical that this orifice is right or you will have oil return problems and possibly loose the replacement compressor. I'm not sure how that would work out using a non OEM compressor.
Originally Posted by Driverfound
The other option one of our quotes gave was to remove that compressor, cap off it's connections, and run it with 3 compressors instead of four. Would that be a reasonable temporary fix to get us through this season, until we can afford to replace that compressor?
I don't see that as a problem as long as it is done in a way that won't cause oil return problems to the remaining compressors. Also, it would need to be done in a way that doesn't affect the hot gas and suction manifolds. When you eventually replace the compressor, that orifice plate will need to be reinstalled and the piping will need to be exactly the way it was originally. In the end, it's going to cost you a lot more money than if you just replace the compressor now.