I installed the Grimmspeed 3 port bcs today. Not quite finished tweaking the wgdc tables, but impressions so far:
Builds boost a bit faster than the stock 2 port bcs, at lower wgdc settings. Able to hold boost longer as well. Car pulls a bit harder up top as a result. 40-70mph time is about .15 faster, versus a pull on the same stretch of road on a slightly cooler day.
The attached graph shows the slight differences. I am still going to adjust some settings, but overall, for less than $150, I'm quite happy with it thus far.
Red line is with the 3 port BCS
Blue line is with the stock 2 port BCS