A $300-$400 turntable tweak

To some extent, there is bound to be a trade off in using a record weight and ring. While you will flatten records and get better coupling between record and platter, you may increase bearing noise through the added weight of those two pieces. That added noise combined with better coupling of the platter to the record, may significantly increase the noise heard through the stylus. It may also render some bearings inadequate or non functional, such as an air bearing or magnetic bearing. On my Transrotor Fat Bob, which has a magnetic bearing, I havent heard a problem using both, but it already has a massive platter and magnetic bearing. On a Rega, you might have a different result.

Rockitman,

I dont know if I agree with your statement that the additional weight will not affect a magnetic bearing. Depending on the strength of the magnet, it may not be able to maintain the separation between the bearing surfaces. And with some magnetic bearings which only lessen the load on the bearing surface, not eliminate it, the extra weight could have a negative effect.

I believe the magnetic bearing in the Project RM10 only unloads the platter from the bearing and doesnt isolate it completely under the same theory that a drain path is desirable. So essentially you have a regular bearing with minimal load and therefore minimal friction and noise with the advantage of a heavy platter for rotational momentum

Perhaps some of the difference we hear with rim weights is due to whether we use a mat on the platter. On my Transrotor Fat Bob, there is no mat, just a vinyl layer which mates with the record. It is hard and has no give so the rim weight just makes sure the record is perfectly flat at is in contact with the platter at all points.
If a rim weight was used with a soft mat, I can see where it might press the record into the mat, causing a different resonant experience than just laying on the mat. I havent tried a soft mat on my Transrotor, and the only one I have is the Oracle mat which is quite soft and squishy.
for the record, I like the sound with the rim weight and center clamp.