I'm not hands-on familiar with the Philips parts, but the 'HC4066 and, of course, the other lower-impedance analog switches are just as effective when the low impedance is required.

This is an old trick, of course, switching the impedance of a filter or current sink by means of various resistor combinations. It was not new in the 70's, when I used it to change PLL bandwidth/tracking range, etc, and it isn't new now. It's a solid and useful way to accomplish what's being done here. Multiple resistances can be parallelled in this way, creating more possible sink current values. The on-resistance must either be known (quite difficult!) or must be low enough to be negligible (more likely in most applications). Fortunately, this on-resistance tends to remain the same throughout a given IC. It does, however, behave as a resistance as it's heated by the current flowing through it. If your resistors are on the order of 10k-ohms, well, it doesn't affect things much. If they're an order of magnitude lower, well, all bets are off. I once or twice used DMOS switches rather than these pseudo-4000-series analog switches. The devil, of course, is in the details.

RE