I'd agree with Tom, you can mix track but you have to be williing to make the adaptations. For beginners I wouldn't mix it. For experience modelers, its not a major issue.
Rio Grande. The Action Road - Focus 1977-1983
I'm going to contradict Brakie here - but not really.
It is possible to mix track of the same gauge with wild abandon - Unitrack, flex track, Peco turnouts, various rail heights (codes,) even hand-laid on wood ties (or directly to a pine plank.)
HOWEVER!!! Be prepared to do some serious shimming, and to get REALLY creative with connecting one rail to the next. The only non-negotiable invariant is that the tops and inside edges of the railheads must be aligned within a (very) few thousandths of an inch.
OTOH, if you don't want the hassle, stick to one supplier.
Just my . Other opinions differ.
Chuck (modeling Central Japan in September, 1964 - with a variety of rail heights from several flex-track manufacturers, plus hand-laid specialwork))
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
I am planning on changing my HO layout over to Kato's Unitrack. If I do, how compatible is this track brand with Atlas code 83 track? There are a few instances where I might want to use the other brand.
thanks