So let me first qualify what I’m about to say by noting that I don’t have an RTSC, just an ETSC and a DTSC. My understanding is that all three are the same device in every respect but the pad shape, but I could be wrong on that point.
When you mention issues keeping the dust collector attached, are you referring to the included bag, or to a full size dust extractor via a hose? I haven’t used the bag a great deal, but haven’t had any issues with the connection. Normally, I’m using the sanders alongside my CT vac with the hose attached. Note that if you’re doing this, you must use the 27mm hose, as described in the manual. The sanders are not designed to work with the larger hoses, nor do they need them: when they have suction problems, it’s almost always a case of too much rather than too little.
The awkwardness of the battery insertion into the charger is a side effect of their decision to prioritize batteries shaped to fit comfortably into the tool handle for extended use. They still use the same charger as all of the other 18v batteries for system compatibility, but the regular batteries are more brick-like with balanced weight across their entire shape. The sander batteries are deliberately back-loaded, presumably with the intent of distributing the tool’s weight evenly instead of front-loading it all onto the sanding pad with the battery attached. But this does make them a bit more finicky to get into the charger since you have to align and insert them using the lighter stem while the bulk of the battery’s mass levers against your fingers.
This doesn’t personally bother me because I prefer the tradeoffs they made: a battery that’s more pleasant to hold when actually inserted in the tool, and a charger that’s interchangeable with all of my others. But if this is your first cordless Festool product, used outside of the context of the regular batteries and their chargers, I can absolutely see why it would be jarring and feel like the charger wasn’t designed for the battery: it wasn’t.
However, the coil whine you describe on the charger doesn’t sound familiar to me. The TCL 6 charger that came with my sander kit is silent (at least to my ears, which admittedly aren’t what they were when I was younger). The SCA 8 charger that comes with some of the other tools makes noise because it has a built-in cooling fan that lets it charge the batteries faster without overheating them, but as far as I know, that isn’t distributed with any of the sander sets at the moment. It may be that you just have a dud charger with whining capacitors that needs to be switched out? Worth reaching out to Festool support and asking about it: they are nothing if not highly responsive.
