I've seen the SI in action and it's really cool. But I'd like to see some more players get in the game to maybe drive the prices down.
Lowrance is rolling out it's new high-def units in Feb 2009. You might watch the clearance pages for Cabelas, BPS, etc to watch for deals on the older models. Also watch for last year's Navionic chips. You can really save some money, but you have to check the pages regularly.