I am a programmer. I also have an 87U 55g, an 87U variable and an HHKB Pro2 (45g).
My 55g is my primary board. As a coder, you're not typing constantly, and I prefer the heavier switch. If I'm typing a ton of documents and plain text, the 55g can get a bit fatiguing at times, which is why I have the other boards. You'll find most guys that make their living on a keyboard have several of them and switch off depending on the work at hand. Obviously, it boils down to personal preference. Nobody can tell you whether a 55g is too heavy for you and your typing style. With all that said, I think you did right getting the 55g 87U. It's the finest board I've ever used.
The above advice to stay with it for a week or two is good advice. Give your fingers, muscle memory and typing style time to adjust and adapt.
In addition, I don't think anybody has mentioned this, but Topre switches need some break-in time. After a couple of weeks of daily use, they will lighten up some.
If I had to choose only one board to keep, it would be my 55g. Stay with it and report back in a couple of weeks. You may just find yourself a 55g convert.