considering the cost of unitrack, can you mix it with atlas flex track assuming the gauge is the same?
Absolutely! I’d say it would be a nice way to avoid having to ballast around turnouts and the track is higher quality than most sectional track. The pros like it for simplicity too, pick up last and current MR’s to see it put to use on a nice UP portable layout… superelevated curves and all!
Just remember that Atlas Code 83 on cork is lower in height than the Kato UniTrack and the rail joiners are not compatible (too big on Atlas side, too small on Kato side).
Isn’t the Kato track closer to code 55? I’d like to know for sure before I buy any myself, since all the flex and etc. will be code 55… I’ve gotten rid of all my pizza cutter-wheels and will never look back! Who needs all that noise and griding and railhopping? ugh… and I am sure the OP will like to know if he’s going to need to use low profile wheelsets?
on the kato website they do not list gauge for sectional track. any ideas? pabdo
thank you: I just checked the kato site again and under faq, they tell you to purchase a transition track which is atlas snap track. again they do not give a gauge! does snap track only come in 1 gauge? pabdo
Most snap track is code 83, the chunky-monkey of track. The side profile is different between vendors, Atlas is fine but snap-track will never run your trains smoothly- it’s ok if you use a little though. Just solder your rails and file the tops/sides to match 
Does soldering feeders to the rail run the risk of melting the plastic roadbed? (Their feed joiners are not inexpensive - used them for an under-tree layout which is now my workbench test / programming track.)
Absolutely not! N scale Kato Unitrack is code 80.
Are you wanting to know about the gauge(distance between the rails) or the code(height of the rail)? There is only one gauge of track in HO and one gauge of track in N scale, unless specifically identified as broad gauge or narrow gauge; there are, however, multiple codes in each scale. Kato does sale a snap track transition piece, but it is not necessary to use it to mix the track. I freely mix N scale Unitrack and Atlas code 80 flextrack without any problems, and I do not use any transition pieces. The Atlas track on foam or cork roadbed is slightly lower than the Unitrack, but you can just shim it up some at the transitions, or shim all of it up if you want it to be level. You don’t say if you are talking about N scale or HO scale, but I would imagine that it would work just as well in HO scale as long as the Unitrack is the same code as the flextrack(I don’t know what code HO Unitrack is).
Are you talking HO scale or N scale? In HO scale, code 83 is the closer to scale track and code 100 is the “chucky-monkey.” If you are talking about N scale, I do not know of anybody who makes code 83, but most sectional track is code 80, which is the “chunky-monkey” of N scale.
You certainly can get smooth running with snap-track. Sure you have to make sure the joints are smooth, but you have to with flextrack also, there are just more of them with
Ah yeah… haha… thank you for correcting me, this is why I shouldn’t type whilst tired. Darn odd work hours. A shame, I won’t be using unitrack in the future… my current project is my last code 80 project 
thanks for your help