The original Schoeps active cables were designed to be supple. Maybe 20 years ago Schoeps changed over to Kevlar-reinforced insulation, which put a real damper on the cables being cut through accidentally. I cycle through my Schoeps equipment every 15 years or so and send it to the factory for checkout, so over time my older active cables have been updated, and I'm glad about that.
--There definitely are more RF sources in the picture than there were in 1973-74 when the Colette series was introduced. The transmitters (a/k/a cell phones) typically operate at higher frequencies than were common in those days, and use signalling systems that produce "edgier" sounds if those signals are picked up and converted to audio (= "detected"). But the main controlling variable (other than transmitter power, of course) is the proximity of the transmitting device to the point(s) of entry and detection in the circuitry. If someone puts a cell phone or pager directly onto your mike cable while you're recording, even a completely balanced system can be subject to audible interference.
It's a "relative" situation with numerous variables. Jerry's right that CCMs are preferable to the modular Colette series if you know that RFI is likely to be a particular problem. But that has to be weighed against the Colette system's interchangeable capsules and active accessories, which the CCM series doesn't have. To me the modular approach still seems essential for most applications, while the CCMs still feel to me like they're for more certain specific applications (e.g. fixed/installed systems). I'm biased, though, because I bought in (literally!) to the modular system early on, and took advantage of its wide range of options. If Schoeps put the CCM amplifier circuitry into a tiny modular package that allowed interchangeable capsules (even without the extra connection needed for active accessories), I'd buy four of them in a flash.
I live in New York City, have used Schoeps microphones to record perhaps 2,500 live concerts and other events (fairly often with active accessories--I use active cables but also active extension tubes sometimes), have heard RF in my recordings only once ever that I can recall, and that was with microphones of the older CMT series (discontinued in the 1970s/80s). That was before cell phones existed, but in the heyday of "citizen's band" (CB) radio. A taxi driver drove by, presumably with an illegal booster amplifier in the trunk. Those could go up to 1000 Watts, and being illegal, they weren't tested and type-approved by the FCC, nor professionally installed for the most part; "dirty" (spurious out-of-band) signals were common. Still, the interference lasted only a few seconds.
In more recent years I've recorded many opera productions with capsules suspended from the balcony of a downtown church on 10-meter active cables instead of the usual 5. By then nearly everyone in the audience had cell phones, and there was never any problem with RF pickup. But those capsules and cables were 10+ feet above the audience's heads--and as I said, that distance matters greatly. Put a transmitter close enough to almost any circuit and you'll get interference.