I started with the M201, I loved it, but it was hard to make it work with mods.
Now I have started to switch over to other pen styles so Here are my opinions on them.
be112: Tight draw like the M201, okay vape at 3.7, but I have heard it is more meant for the 5v. I got this one with my SP mod from litecig. It is cost more than me M201 sadly.
$9.95/ea. copper.
Joye302: Lighter draw, but plenty of vapor for me. It works well with my SP, dse801p/t, and my dse905 with the 901 to 801 adapter. A nice 3.7v vape. It also is a good price too.
$7.95/ea.
RN-4072: A little tighter of a draw than the 302, and equal vape. I have had to use the "staple" mod to get it to make contact on my 801p/t and ma DSE905. The other problem I have had is that the carts are either too tight or too loose, it can be agrivating when I cant get one off to fill or the cig slips off the cart when I dangle it from my teeth. Price is good at $7.95/ea.
DSE801: Lightest draw and least vapor for me plus long break in. It also has a rubber bit tip, I do not like that, but some do...
$7.95/ea
I do like the RN-4072 a tiny bit better, but the overly tight or loose carts and having to bend a staple up and not lose it when you change atties kills it for me.
I would say out of the four the Joye302 is the best replacement for the M201. It should work with any mod that the 801 works on and is a good vape.