Doesn't sound like much of a controlled study. Selection bias may have played a part :P
Even just having a physically larger display that fills your FOV appears to improve spatial task and memory performance: http://research-srv.microsoft.com/en-us/um/people/desney/pub...
From another study (http://pro.sagepub.com/content/56/1/1506.abstract) on actual satisfaction (not open access, so quoting some key bits):
First, they provide a good summary of previous findings:
"Previous research has demonstrated productivity increases for users performing tasks on larger or multiple screens. For instance, a 9% productivity increase was noted while using wider screens (15” flat panel vs. 46.5” curved screen)
(Czerwinski, et al., 2003)."
"Similarly, a 3.1% increase was noted using dual screens over a single screen (Poder, Godbout, & Bellemare, 2007). Task success has been found to increase for tasks performed on 4 – 17” monitors vs. a single 17” monitor (Truemper, et al., 2008). Likewise, tasks were performed faster and with less workload while using 2 – 17” monitors over a single 17” monitor (Kang & Stasko, 2007)."
"Other studies have noted increased window interaction and open windows while using multi-monitor configurations (Hutchings, Smith, Meyers, Czerwinski, & Robertson, 2004)."
"Issues with single monitor use have been well documented. Generally, higher mental workload, more window switching, repositioning, resizing, inadvertent opening, and closing of files have been associated with single small monitor usage (Czerwinski, et al., 2003). Users generally perceive small single monitors as requiring more workload (Grudin, 2001; Hashizume, Kurosu, Kaneko, 2007)."
Second, their own findings:
"Participants felt more rushed, that they worked harder, and were more frustrated [with a single monitor configuration]."
"Participants spent more active time in the PDF reference document while completing tasks on the single monitor configurations"
"Participants were observed to leave the PDF reference document open and viewable (but not in focus) while working with other source documents when in the dual monitor configurations."
"Participants clicked less during tasks on the dual 22” monitors than the dual 17” monitors and single 17” and 22” monitors."
"Participants switched between windows more frequently during tasks on a single 17” and 22” monitors than the dual 22” monitors."