there is no mac equivalent of Harmor. I've got a "try before you buy" version of Alchemy, it sucks. HARDLY decent resynthesis - what Harmor is doing is additive resynthesis, similar to NI's Razor, but with the ability to utilize a shit-ton of partials (harmonics) for the resynthesis process.
I suggest looking into spectral cross-modulation (Kyma TAU morphing, Amon Tobin, etc) if you're really serious about resynthesis.
I did crack open my copy of Razor and change the partials available per-voice from 300 (or whatever it was) to 1200, and it made quite the difference, though it also made quite the difference on my CPU
that being said, I've turned to Max 6 lately for spectral cross-synth type shit. Also look into Phase Vocoding, it's similar. IRCAM has a dope phaser vocoder, but shit like this, will not be available on torrent sites - gotta buy that stuff man.
Iris is a sample-playback joke. it's the illusion of spectral cross-synthesis, but it's working in the time domain, not the frequency domain, which is what you want.
essentially, you want to find the highest-resolution way to impart the spectral characteristics of one sound, onto another. This can be done in Kontakt with AET filters - but I've found best results with around six groups of "growls", and each one is modulating another, round-robin group-triggering, and ultimately only imparting specific characteristics onto the main sample.
This takes time, as you have to define AET morphs tables for each sound that you want to apply an AET filter to, and then apply those filters to each group... flowcharts help for anything more than 3 groups
Seamless may make Harmor seem like the "holy grail" of growls, but really, I get dirtier, filthier things from FM8, Trash 2 (long subtle chains) subtle convolution (can be made to "fake" cross-synth shit), modulation of multiple notches in pro-q, resample, apply more convolution, more multi-band distortion, resample, ad infinatum.
It helps when resampling to tag version numbers onto your new, precious growls; e.g. "The Snarlax V3" - stay organized!
I've applied spectral cross-synth patches in Max to various samples, and really it's DOPE, but it's a crap-shoot. because I don't have a Pacarana (you know, the $4500 box of CPUs that Kyma uses for TAU morphing) - thus I can't do it in real time, so i record like 2 minutes of cross-synth stuff (say, a few growls) offline in Max, so CPU cycles aren't an issue, and then i cut out the best parts.
The following synths, available on a mac DO NOT do what you're looking for:
Alchemy (too few partials, and the "noise" oscillator is a joke)
Iris (it's an over-priced, pretty looking cross-fader)
Electra X (damn good synth, but not the same)
Gladiator (nope)
Massive ( don't even try. and PLEASE don't add to the ever-growing collection of youtube tutorials about how to do this with just Massive, there is no taking the elevator with this sound - only the stairs)
Razor (won't do it out of the box. have a full version of reaktor and prepare to get your hands dirty)
Kontakt can do it with 4 and 5, but setting up AET morph tables was a LOT easier for me in 5 (for whatever reason). Bear in mind that it's not going to sound like Harmor, but define your own sound. a "Growl" is such a vague term. Yes, I can make KTN, Zomboy, Skrillex, Datsik, Excision, bass lines, but why do I want to? They do a pretty good job of it
Not sure about Rayblaster tho, it seems like there's a resynthesis option, but i've got my workflow down so well now, I'm making bass samples, and not trying to learn that synth at the moment.
Harmor: Just additive resynthesis with a lot more partials. trust me, this isn't easy.
I know you're probably looking for something similar to Vocodex for osx as well, only thing that comes close is Waldorf Lector, unless you pay me good money to run your samples through my souped-up version of Razor's vocoder! Remember tho there's a lot more to using a good vocoder than selecting the carrier and the modulator though.
You CAN run a sample into FM8 as a modulator, but you need to be VERY subtle about it - or the output pretty much turns to white noise.
I've been down this path. I watched some "how to bass" vids, was blown away, and hadn't done much with my Max License. If you decide to do the research, and are anything like me, you'll be reading DSP papers on your computer or tablet in bed at night. You're entering the dark realm of academia here, and DSP is no laughing matter. Unless you're an engineer, you'll wish you paid more attention to math(s) in school.
good luck, and long live the Fourier transform!
/geek