Anyone have a suggestion on this set up? I was going to use the 10SI on the console and the 9DI for the Bow. But I'm a little unsure if both need the combos which consist of XD mapping installed! So before I buy these units please give me suggestion, info and knowledge on these Hummingbird Helix units.
Thanks!

You have no choice about mapping or not, they have ContourXD mapping built in. You can add Lakemaster and Navionics mapping.

Exchange the included transom DI transducer for the proper trolling motor puck that has extra internal shielding.
The XTM 9 DI 25 T is tuned to the same frequencies as the transom transducer.
The XTM 9 WIDE DI 20 T is tuned for 83/200 kHz 2D sonar.
You choose the 2D coverage you want.

I am running Helix 10s(2) at the console, (1) with an in-hull transducer, and (1) with the transom mounted SI transducer. Also running a Helix 10 at the bow with the SI transducer, using the transducer shield and saver on both of the SI transducers(trolling motor mount and jackplate mount) and Love the setup. I like using the transducer shield and saver mounts due to the fact you dont have to drill holes in the boat and also they provide a whole new level of protection for those expensive transducers. I am currently using the Navionics Nav+ in on unit and the Platinum cards in the other 2 for my mapping. The units have a great screen that shows great detail and the ease of use is incredible straight from the box.

That sounds like an amazing set up! Dollar wise I'm willing to bump up to two Helix 10 SI's since yours work so well but I never thought about side imaging on the troll motor. Wow, did you have yours professionally installed?
Thanks!

great choice!!...No, I installed them myself, but I do all of the rigging on my boats each year. With the transducer mounts that I spoke of above and the Bass Boat Technologies graph mounts at the front and rear, it really does make installing these units very easy. Since the units have the internal antennae, you only have to run the transducer and power cables, not bad at all.

I just recently had 2 Helix 10's installed. I was going to go with a 9" on the front and 10 at the console until I was told that in order to link the 2 units they needed to be 10's. Any way points I mark on the bow unit automatically register on the console and vice versa.

Somebody gave you bad info. The 9 can be networked, they just don't come with the hdsi transducers.

The 9 and 10 can be connected and you can share way points. You can also get side imaging on the 9 from the 10. Only problem is you are reading side imaging from the transom.