Speedfeed stocks are extreemly high quality, many would argue they are the best synthetic stock (come factory on remington police model and some others, and used by people like scattergun tech/ wilson combat). I think they are unsurpassed in fit and finnish.
With that said, I think the tactics of reloading from a speedfeed stock are weeker than reloading from a sidesaddle. Also you are limited to four as opposed to six rounds.
But, I have speedfeeds on 4 different shotguns, all one holding the extra rounds. I outway my perceived weaker tactic by the unlikelyhood that I would have to reload as well as the fact I bassically want the rounds there to top off the firearm from cruiser ready as well as just keeping a couple slugs in case. Also I probally wouldn't carry the extra rounds if it wasn't for them.