I have now owned both so I guess I can give my 2 cents. I got to do a side by side test on them before I sold my Lyman on ebay last week.
The first thing that I would like to talk is about the price difference. Now the price difference is about $50.00 and not that large when consider all the other cost of shooting and reloading.
RCBSand I saw the Lyman on sale for $209 somewhere?
Ok the next thing is the speed everyone is talking about. If you are loading for the smaller grain cases around 50grs or less then the speed is the exactly the same on both units. I tested my 22-250 load of 36.1 grs varget and they both filled the pans at the same time. But when I put in 100 grains the RCBS is much faster, maybe even half the time the Lyman takes. This isn't that import to me since I shoot the smaller grain loads in high quaintly, I don't plan on shooting 1000 rounds of 300 mag any time soon.
Warm up time! The Lyman takes forever. But the Lyman does say that you do not have to let it warm up but it may not be as accurate. You don't think this time is very much but if you use it a few times it adds up fast.
Accuracy they both seem to be the same with the scale. Both scale read the same, on every test I did. One problem with the Lyman is that it seems to throw overcharges more often then the RCBS. For those who have never used one of these I am talking about the dispenser putting out 36.2 or 36.3 when you wanted 36.1. This isn't a huge deal because the scale shows that it is the wrong weight but you than have to remove .2 grains or dump the whole charge back in the hopper and dispense again. Like I said this isn't a big deal but is kind of like the warm up time it is just a pain and a few of these get old quick.
The last two things is the noise and clean up. The RCBS is almost silent and the Lyman is loud when charging. I think the cleanup on both of the sucks. The RCBS seems easier but the little tube the powder comes out of is small and you need to make sure you get all the powder, this is very import if you use different powders. The Lyman is a pain because you need to take out the charging tube.
Over all I like the RCBS a lot more. They both are good units and should work for most people but for the price I would buy the RCBS again.
I hope this helps .
Mark