802.11g WiFi standard specifies at least 11 channels across the band (in some national jurisdictions there are 13 channels available).The new 2.4GHz operates between 2.402 and 2.480 GHz....that's a range of 78MHz to find a clear channel
For normal computer data rate purposes the channels overlap some what and there are effectively 3 usable 20MHz data channels in the band in most localities, but the data rate for a Model Railway control purposes is most likely quite low in comparison and require a lower usable bandwidth, so that may not be a consideration.
What may well be a consideration is that the whole 2.4GHz band has become quite congested in populated areas as household internet usage has increased. In high rise MDUs (Multiple Dwelling Units), 2.4 GHz Wifi is often only barely usable due to the number of dwellings contending for bandwidth. Also, there are an increasing number of IoT (Internet of Things) gadgets using the 2.4GHz band in many households... we have several Dyson fans, Cygnet power switches and Apple Homepods using the band in just our home and I can see the number of such devices increasing overtime as more domestic devices/appliances come with IoT control features enabled.
Where I live in suburban Sydney, the housing blocks are quite large by UK standards but when I scan the 801.11g spectrum, my WiFi monitoring software can "see" about a dozen WiFi networks from other nearby dwellings. The signal levels from those networks are significantly below that of our household 2.4 GHz band WiFi access-points but there are times when our gadgets on 2.4GHz band do have trouble responding promptly.
We use the 802.11n 5GHz band for our computer data nowadays (as it has more, and wider channels).
Anyway, the point is that the whole 2.4GHz RF band (which is mostly unlicensed) is filling up with lots of stuff for various reasons, so if you live in an area where dwelling are close together, simple congestion might be an issue too!
My Massoth 2.4GHz Navigator bits have not yet arrived, so I can't specifically comment on Navigator performance. I have an upgrade for the older Navigator coming, plus a second-manufactured-as-2.4GHz Navigator, so will report on my experiences when they arrive.