I recently got an HDS 7 I am quite happy with it but I will tell you the navionics chip is a complete rip off. Not only is it lacking a lot of details (they blame that on the canadian government) but you can get the navionics app which has all the charts and an even bigger area than the chip for $15 on your iphone but it costs $200 for the chip for your GPS. What a joke it's more then 10 times the price and from what I can see offers you nothing more than the iphone app except you can see it on your gps instead of the phone. Maybe just get an ipad if your sounder is already good and buy the navionics app. That said if you got an HDS 8 you can add radar etc. etc. to it later which you of course can't on the ipad but if your just using it for gps and nothing else it is something to at least think about. Not sure how an ipad would hold up on a boat but they probably make some good cases for them.
I'm sure other brands also require a chip and it is probably the same rip off but maybe a brand like standard horizon comes with charts? I'm not sure but pay attention to what charts your system will use, how much detail they have and the cost because it should be a factor in your decision.
Other then that I am happy with the unit, the sounder works good even with the 83/200 transducer. I don't find the unit to be really user friendly it can be difficult to figure out how to use some of the different features and it takes awhile to set up the screens how you want. You've used lawrance before though so you'll probably pick it up fast.
If I was to do it again I would seriously consider a simrad with a touch screen but it's quite a bit more money. I find I'm always trying to use the screen as a touch screen though I guess I'm too used to my phone.
Also you just missed the weekend getaway event where you would have gotten a $200 mail in rebate but you'll probably get the gen2 HDS8 I think the rebate was just for gen 1. Not sure what the differences are. Cabela's had a great sale in their US stores back in November $150 off plus I got a $200 mail in rebate if your going to be south of the border before christmas it might be worth waiting to see what deals there are next fall.