We are a Fortune Auto dealer as well and I have extensive experience with these units. Hopefully I can bridge the gap for you guys.
The 500 Series is their basic set. It is comparable to the BC entry level units. BC uses an old Ohlins design, so the valving is OK, but the springs are poor. This is very common to most entry level coils on the market. The Fortune Auto 500 series also has a very basic spring and standard valving. The Fortune Auto is fully rebuildable and upgradeable in the US.
The 510 Series is a very different coil from the 500 Series. The 510 is a good option for the track enthusiast. You will find the Swift spring option a very smart upgrade as well. Swift make one of the best springs on the market,and paired with the 510 Series, you have an excellent alternative to the KW Ver3.
The KW V3 is a very good shock albeit a little soft for competition use in its off the shelf form. The KW has exceptionally good manners on the street, but that can be its shortcoming on the track. You will find you will want a little more adjust-ability once you start getting to the limit.
SO the 500 and the BC are very similar. I think the Fortune is aesthetically more appealing, but that is just my opinion. The base models will perform very similarly. The 510 is a far better unit and add the Swift springs and you have a very nice setup indeed. It(510) is very similar to the KW, but the Fortune has the Swift springs which are better than the KW springs. The KW, however, maintains the stock style rear....spring and strut separate.
I hope this helps a bit. Feel free to email or PM me with any questions.
John
John@AkumaMotorsports.com