Upgrading my Williams by Bachman 4-6-0

Good choice; I've done 2 of them, one with a different tender and lettering and no sound, the other with sound in the stock tender.

The gearing is so good and low that you don't actually need a Cruise Commander, the plain DC Commander will do. The plastic tender makes antenna installation a snap.

To answer you question: no, you do not give up conventional control when installing command control. The motherboard is, at heart, a reversing unit (an electronic e-unit), and when the radio (receiver) board does not sense an operating (plugged in) command base, the system "reverts" to the F-N-R conventional operation - though why you would want to do that, I don't know.

You'll like it a lot; good, friendly starter project loco, with a big, roomy tender. 

The Williams 4-6-0 runs so well, and is proportioned so nicely, except for the oversize tender, I think it's worth the upgrade. I'm currently trying to upgrade the smoke unit in one of mine with a Lionel fan driven unit.

Thanks for the answer D500. I saw some of your other posts regarding the WBB 4-6-0. My plan is to do a DC Commander board, a railsounds board and a new smoke unit. 

BRR I'm interested to know how that conversion goes.

I hope you're considering the Cruise Commander and not the DC Commander.  The DC Commander doesn't offer cruise.

While you're at it, maybe you'll consider some cosmetic upgrades.  Here are a few ideas:

I posted a detailed thread on the modifications last summer, if you're interested in more detail.