Curved and Straight Tonearms


Over the last 40 years I have owned 3 turntables. An entry level Dual from the '70's, a Denon DP-52F (which I still use in my office system) and a Rega P3-24 which I currently use in my main system. All of these turntables have had straight tonearms. I am planning on upgrading my Rega in the near future. Having started my research, I have noticed that some well reviewed turntables have curved 'arms. My question: What are the advantages/disadvantages of each, sonic or otherwise? Thanks for any input. 
ericsch
@yogiboy 
I doubt he is looking at a vintage separate arm!

I mean if someone would like to compare S vs. J on the same arm the Audio Craft and related stuff with removable artubes is a good option to understand which shape is the best for the owner. 

I have 2 "S" shaped tonearms and 4 "J" shaped tonearms and i can't say which one is better based just on the armtube design. 
@chakster
Gotcha!
 IMO,cartridge and arm matching is often overlooked when evaluating the performance of an arm! Do you agree?
My question was prompted by the TAS review of the Technics SL-1200G in their current issue. I'm looking for a table under $3500, not vintage. I like Rega products, but I want to be able to use different cartridges and adjust VTA without using shims. I currently use an Exact 2 in my Rega.

there are perfectly straight arms, but they're mostly used for DJ scratching.

the rest of arms as pointed prior either curved or with s-shaped tube.

Most DJ arms are "underhung" to aid in scratching, whereas straight tonearm with an offset headshell used for accurate audio replay are overhung.