Even though you say your not a 'bass head' I'm guessing you still like a fairly bass heavy headphone, as this is what the Fidelio's are known for? Imo they probably have the best bass out of all the headphones I've heard, well weighted, great sub bass, but also tight and punchy!
I'm sure you'd be very disappointed by the WS99BT's which will sound flat and lifeless next to the Fidelio's! They need some serious EQ to sound anywhere near decent imo. If you like a more balanced, neutral signature then they probably sound OK, but I'm guessing this isn't what your looking for considering you said the Fidelio's were perfect for your taste.
The Harmon Kardon's were on my shortlist too, but after some fairly extensive research it sounded as if they wouldn't quite cut it against what is available now.
If you want the Fidelio's sound signature then I'd highly recommend either the Onkyo H500BT or the B&W P7 Wireless. All three sound very similar and I'm sure you wouldn't be disappointed with either pair! Both have great separation, clear mids and treble, and a great sounding extended bass. Comfort is very subjective, the Onkyo's would be the most similar to the Fidelio's being On Ear, and I found them more comfortable than the P7's because of how light they were and their low clamping force. I also found them more comfortable than the Fidelio's too. Despite being less comfortable I actually preferred the fit of the P7's which are Over Ear, and to be fair it's probably more down to wearing glasses that made the Onkyo's a better option!
I found a secondhand p7 wireless for $250 in good condition just two days ago. The most expensive headphone i ever bought. I have listened for several hours now.
I like the precision of the drum sounds. Snare, Kick, and especially Tom sounds really accurate. I listened to daft punk's RAM album and Foo fighters' Wasting light album, and the drum sounds completely fresh. I really really like it.
However, I don't like cymbals sounds of p7 at all. It lacks of clarity. It sounds like there are two guys there. One powerful guy, in the center of the stage, is in charge of snare, kick, and toms. And the other guy is in charge of cymbals, he sits far from the center and have less power.
Bass sound is heavy, but thanks to the excellent sound separation which prevent the bass to destroy other frequencies. Without equalizer, bass of this cans is too much for me. Compared to fidelio, it has similar quality of bass, but the quantity on p7 is much larger.
It's a good looking headphone and the pad is comfortable. The pressure of the clamp is placed at lower side of my ear. It gives me less fatigue compared to my ATH-M50.
Overall, it is a fun headphone to listen. It handles complex music with many instruments really well. I will grab it for 90% of my playlist.
I am still thinking to compare it with other headphone, and decide the keeper. How about Parrot Zik 3. Does it handle the cymbal/treble sounds better?