Does anyone know if it is it easier to open a door with rubber compression seals around the thin side of a door, or with felt around the thin side of the door?
I'm not sure what you mean here.
Sealing a door with felt is based on an entirely different acoustic principle than rubber gaskets.
Felt is NO insulation material but absorption material. This even means that you don't need pressure on it. It absorps as splitter silencers do.
But that also means that the resulting TL depends on several factors.
If you should use a felt with a width of 1/2" as substitute for a rubber gasket of a simular size, I can assure you that the felt is a very poor choise.
If you use felt as an absorber to seal the door you should use the complete door thickness to create a long absorption path. And the insertion loss then is mainly defined by gap width versus gap length. So this technic is mostly used (if used) as an addition to, or supported by other types of sealing. This technic also solves potential resonances (modes) in the gap.
But the best thing is still good rubbers. One of the main problems with a good door is designing it to get enough pressure on the rubbers.
And that's defined by the quality and type of the latch (+ rest design of course), which should build up pressure in a conical manner.
Those magnetic sealings are an in between solution. In fact they are meant to solve inaccuracies and guarantee a perfect mid, high frequent sealing.
But the design of a magnetic seal is as such (mainly designed for thermal purposes) that you have a feet and this magnetic stripe which are connected by a VERY thin elastic housing (allowing relative large expansion), with relative poor insulation values. So a magnetic sealing can solve large gaps but at the expense of TL. (I hope you understand what I mean here)
So counting on magnetic sealings for very high insulations doesn't feel right to me.
When having a sound lock with 2 seperate doors of around 30 dB than it doesn't matter that much.
Professional acoustic doors (ca 50-52 dB doors) with double sealing will show a total pressure on the rubbers easily exceeding 150-200 kg (330-440 lb). This only works with good door accessories (hinges and latches).
Does this work easily? Yes it does.
I've used lots of such doors in TV (and other) studios. Those on TV super sexy looking assistants who have to guide people to their places and different rooms, if you see them in real live without/before make-up, it are almost children (no disrespect meant) with a weight of 45 kg (100 lb). The door leave is about 2.2 to 3 times their own weight.
Well a TV station can't permit herself to have those assistants starting a fight (in front of public, visitors, artists, VIPs) with every acoustic door they encounter. They only have to learn to act calmly (mass ratio door versus assistant)
So it's all a matter of defining your goals and targets and adjusting your design in accordance to that.
Best regards
Eric