I am looking to purchase a 998c.  I currently use a 798c at the console and  have an in-hull for high speed and SI transducer on the jackplate.  They are connected using the y-cable.  
Regardless of speed, I understand that the y-cable will always use the in-hull for 2d sonar. I have tried everything and unfortunately get very inconsistent readings from the in-hull transducer.  Because the readings are inconsistent with the in-hull transducer, I want to use the SI Transducer for low speed (less than 5 mph) as I am sure it give me better readings as the sonar signal is not through the hull.  Before I started using the y-cable, I used the TS2 W Switch.  Generally, will the y-cable give me better readings than the switch or is the y-cable just more convenient???  I do not mind using the switch but is it more difficult (wear and tear) on the unit than the y-cable?
Thanks