Ok, heaps of opinions here so I'll just add some bits n pieces.
First off, Every engine is different, and bolting a generically tuned ECU like SPOON, MUGEN etc will only reach about 50% gains compared to a Custom tunable ECU. This has been proven countless times locally here and over east. You will encounter problems like running too rich or lean, and timings are never accurate simply because all engines are different which is more of a factor than different mods suggest.
If you don't have a nice honda tuner in your country and skeptical, then you should just buy a bolt on generic ECU, but you'll be very limited and can only do very basic mods... If you have a tuner around, 100% go with a custom ECU and start making power.
I agree with many of the users here regarding power dips with a lowered vtec point on generic ECUs... I've just recently installed a buddyclub V-CON to lift back the VTEC point to 6000rpm on my Js racing ECU. Now the power delivery is beautifully traditional with that sudden kick that all type Rs give you on your 1st time experience, EXCEPT now I have 9100rpm redline from my J's ECU, so my power band is longer and now without DIPS, also that terrible retarded vtec barp sound that you get under 6000rpms is gone.... Now its vroooooooooooooooom...BARRRRRRRRRRRRRRRRRRRRRRHHHH! nice and original!
I really didn't like the power dip especially now after experiencing the V-CON mod, I'll never lower the vtec point again unless it'll make power. Buddy club V-CON only cost me $40USD delivered from EBAY. Theres only 1 seller in the US that sells this on ebay. This is the best mod I've done to my generic ECU, I reccomend it to everyone.
Ive searched up the net in regards to this V-CON and heard heaps of bad sh1t about it. I've heard stuff like stuffed up vtec crossover, redline reduced to 5000rpm and other bad sh1t. This is probally because they've installed it wrongly which can happen or they all lower their vtec down to like 1000rpm which would cause serious damages.
But after installing the unit, which was pretty easy, it worked for me 1st time off. I set it at 6000rpm, and thats it. No probs, no faults.
The unit simply taps into your vtec line on your ecu harness and re-adjusts the vtec point coming from your ecu and sends it to your vtec solenoid. Highly reccomended if you have power dips with generic ecus.
Also, someone mentioned they had a MUGEN ecu and had noticable dips from 5000rpm till 5500rpm. I believe this all depends on the timings programmed on the ECU. For example, My J's Racing ECU made me gain a massive 5-10whp and torque to match between 3000rpm-5500rpm with my mods. ECU Timings contributed to this more than my intake and exhuast etc etc.
Overall, you can see how results all vary quite a bit. Thats why YOU SHOULD GET A CUSTOM TUNED ECU. I've also posted some stuff before in regards to DC5R tuning. They compared a custom tuned Hondata K-pro to a generic MUGEN ecu for DC5. And the Custom tuned HONDATA K-pro made up to 8whp more everywhere. AGAIN, simply because ALL ENGINES ARE DIFFERENT.
Winston: its really amazing to see the SPOON ecu work so well with yours, maybe you should try a different dyno to see any difference because I've experienced different power lines on different dynos. Try one that measures WHP, otherwise mate, your very lucky!