Yo Malcolm! I won't try to compare the two pres in question, because I don't use either one, although I'm familiar with the spec's, and a cross section of Homerec opinion, like you. But- here's my spin on "color". Color is subtle distortion, that we like (sometimes). It is like airbrushing a centerfold to decrease the distraction of annoying detail. In the case of mics, this can be lip smacking, stomach growling, or uneven frequency peaks/stridor. Often, this includes crossover frequencies from other instruments or voices, or room reflections. Color is more often used on small ensembles and soloists for this reason- The more signals you have, the more likely it is that the color you liked so much on a source will cause it to get lost in the mix. And- the quality of the source is critical. If you are recording Pablo Casals on a $400,000 cello with a $60,000 bow in a perfect room, clean is probably the way to go. What kind of color would you want that he hasn't already got, either through skill, or by paying for it? Some babes don't need to be airbrushed. The better the source, the less color I want, as a rule.
This is a spectrum, though. *All* preamps produce some distortion, and even the cleanest preamps have their own sound. Guitar amps- big-time and on purpose. Mic pres- much more subtle, and not always on purpose. When we don't like it, "color" becomes "muddy". *Some* distortion is good *sometimes*, and some distortion sucks *all* the time. Amps that use tubes may be using them for power, and may produce very little distortion, or a lot more, depending on the tubes, the design, and how hard they are pushed (saturated). Amps with a small tube in the front end are *trying* to use the distortion-producing properties of the tube to produce color (warmth- the good side of "color"). Many of the priciest preamps, both current and vintage, are prized because they produce *wicked* good color. It may mean they're not right for everything, but for some things, they may be perfect. You don't need tubes to get good color, either, as the solid-state Neves mentioned above have proven for years.
My advice to most project studio beginners is to start with the two cleanest matched channels they can afford. When the preamp has to do everything, clean is more versatile than colored, and generally better for stereo recording. Then, over time, they can add the colored channel(s), when they know what they like, what they need, and what they can afford. Really good preamps, whether clean, colored, or in between, are Godawful expensive.
Hope that helps.-Richie