“Test-Diving” equipment before you buy is always a good idea. You would not buy a car before researching and test-driving it. Some LDS may be reluctant to let you dive gear before you buy, others may not. If the LDS has a pool, than your chances are much better to try out the gear you like first. Furthermore, if it is “common” gear, they may have rental equipment which you can use during a weekend outing.
Another possibility is to check with the manufacturer, since many offer demo-days. The sole purpose of a demo-day is that divers can “test-dive” their equipment and ask all the questions they have. Quite often these demo-days are also a place to socialize with fellow divers.
So look around and “test-dive” as much as possible. Each BCD handles a bit different, and there are quit big differences between more traditional jacket-style BCD’s and tech oriented wing-style BCD’s. Have fun!