Beyond 6.310, Humminbird made some major changes in the software that kinda screwed up the 2D sonar ..... I think it hit the 1197 harder than some of the other models.
If you don't have any accessories that require higher than 6.310, the best all round imaging and features are 6.310.....The 360 can't be used on the 1197 anyway.....Ipilot link and heading sensor would be the other things that need a higher revision, and they are supported by the 1197.
There has been an update to the 99 and 98 series to improve the 2D problem, but the 1197 hasn't gotten this release, and I don't know for sure if it will or not.
I have an 1197 and I don't think I will ever update it beyond 6.310.