i don't have any experience with lakemaster but have been using the navionics app for a couple of years and find it reliable.view their webapp to see the lakes and detail they have be sure to change the contour mode to sonar charts to get the detail.
http://webapp.navionics.com/?lang=en#@6&key=kwoqFn~ylM
Another consideration is that Navionics plus gives you access to maps for the entire country and canada not just a specific region and includes 1 year of updates.
Also check the mapping functionality of your unit to see if it requires lake master (depth highlighting for example)
These guys are having a fire sale on Navionics
http://www.gpsnation.com/navionics-micro-sd-card.html
