Connecting a standalone Microsoft R Server to a SQL Server with R Services and a SQL Server without R Services
I can answer some of these questions hopefully:


The standalone machine has the benefit of most of the machine resources at its disposal.  However as far as benefits "while connecting" go, there are none. The point of SQL Server with R services is to keep the analytics close to the data.  This has little or no consequence for external clients connecting to the data, as I see it at least
you can invoke SQL Server stored procedures from R using the RODBC library, for example this worked for me:

install.packages("RODBC")
library(RODBC)
dbhandle &lt;- odbcDriverConnect('driver={SQL Server};server=.\\sql2014;database=tempdb;trusted_connection=true')
data &lt;-sqlQuery(dbhandle, "EXEC sp_who2")
data
odbcCloseAll()



Results:



push compute is a feature of the ScaleR library, eg function RxInSqlServer.  See here for more details.
regarding "anything special that SQL Server with R Services offers for a standalone Microsoft R Server...", you could conceivably call the R stored procedure sp_execute_external_script from R using RODBC, but this seems a bit pointless.  A dedicated SQL Server box (ie without R Services enabled) does not have to share its resources, and this kind of answers your last question I think; the point of having a dedicated box of either kind (MRS only or SQL Server only) would be so that neither has to share its resources.  The point of having a SQL Server with R Services enabled would be so the box could perform dual roles, resources permitting, plus keeping the analytics close to the data.  I hope that makes sense.


Here's a nice article on persisting machine learning models to a table using SQL Server with R Services.  How would you do that in standalone R?

Maybe someone else can chime in because honestly this seems very similar to your other questions.  You might guess not that many people are doing this so one of the best people to do this is you; try these things out, report back : )