I have used both the Speedfeed and the Choate, and really liked the Choate for its extra thin profile, it is about as minimalist as you can get. I still have a Speedfeed on one of my less frequently used 870s, and it gets the job done, but honestly I find the rarely seen yet excellent synthetic Remington Police forend that mimics the lines of the wooden forend on their standard Model 870P to give the very best feel and control.
Since you expressed that you had no interest in mounting a vertical grip on the forend, this may be one to consider. All of the older patrol officers in your area will also look at your shotgun with fond memories. Brownells still carries them, (767-000-083 F106560 FORE-END, SYNTHETIC, POLICE) for like $35, though none of the Remington line on their website wears one, and the wooden model is only available on one model on their Law Enforcement site.