Hi,
If you have the funds the Canadians like the ABI are fantastic basses. But finding the color/configuration you want may be difficult on the used market and if you order a new one there is quite a long wait time unless you find a dealer who has one already on order.
Pres: Difficult to describe but I will give you my impressions.
Canadian Glockenklang = Pristine, Clarity, smooth extended top end response. Appropriate, IMO, for most any genre. Add a pedal for grit.
Darkglass available in NG2/NG3 and in the Canadian basses: Has a low mid and high mid versus a "traditional" low, mid, high. This gives one the control over the all important mids. It is a clean pre but can give a bit of grit/growl and is probably considered the top of the lineup especially if you are a rocker. Metal guys love it. But on the other hand, due to versatility, it can really be used for most any genre music. We have seen Country players that like ita lot We sell many more basses with the Darkglass than the other pres. The low mid, high mid control is so nice as this give an almost unprecedented control over these important frequencies for bass guitar. It is my favorite pre for rock.
Combustion with EMG. I have to say that, IMO, as much as I love the Darkglass pre in the NG2/NG3, the Combustion is a bit more versatile bass over the NG2 /NG3 with the Darkglass. The output is clean and smooth. If a person wants to play Jazz, Clean Country, or simply likes the low, mid, high control, this is a nice pre. But on the other hand, it is entirely appropriate for rock. And if a person just wants that Darkglass growl, simply add a Darkglass pedal. We sell far more NG2/NG3 that Combustion, but IMO folks should strongly consider the Combustion as a bit more versatile a bass/pre.
Now NG2/NG3. You will probably only fine new NG3s as they have been on the market for a short time. We have had a few NG3s and actually were able to do a bit of comparison. To me, there is an obvious difference. We were listening to these last weekend at a guitar show where we were displaying several NG2/NG3 basses. One comment by a player when he tried both, and also what I heard, was an immediate increase in presence with a bit more pronounced and clearer low end. But this was not an extensive comparison/test but just initial impression.
IMO, as a bass player, I really wouldn't mind, and would actually be delighted, being on a stage with any of the configurations as I like all of them.
Hope this helps.