Hi,
You doing it the right way, having done most of the mods to get most out of the ST24. I have BLUEFIN on mine and it did improve the driveability, but you won't see any top end improvement. Dreamscience also do a plug in map, which has 3 levels of tune, bit better than BLUEFIN, but the best is always a dedicated map to your car, as all ST24s are not the same, and as you have done most of the main mods, you will benefit.

When I got my BLUEFIN years back, Dreamscience weren't around, but they are quite big now. What I liked about the BLUEFIN was you can set it back to original settings when you want and it will also show you ECU fault codes, but depends what you want.