Check out Ellen C. Brotman's (Montgomery, McCracken, Walker & Rhoads) article: Make Probation a Real Option at Sentencing, 23 Federal Sentencing Reporter 257 (No. 4) (April 2011).  Her opening line: "My advice to the Commission is to amend the Guidelines to establish probation as a distinct type of sentence with independent value, rather than as merely a lenient option to be used only in extraordinary cases."

(esp)(hat tip to Evan Jenness)