The answer is as easy as this: Would a potential buyer consider those properties if they were looking for a place like your subject? That is all that matters. When you are talking about Townhomes as single family, it is better to use the term "single family attached" as this describes the ownership rather than design, as there are also townhome styled condominiums.
With that said, your description of the single family attached homes appear to be valid substitution properties in the market. While single family attached homes usually have a small amount of land attributed to them, this land is usually nominal, and somewhat similar to the undivided shared land of a condo ownership. If all the amenities are similar, design is similar, and characteristics are similar, then it is a comp.
To the above thread, it doesn't matter what the future appreciation rates might be in SF vs. Condo, because you aren't appraising the future, you are appraising the marketability of your condo at the present, and if the single family attached properties are competing with them right now as a viable substitution, then they can be used. Like I said, let's not be guilty of hubris here, all that matters is if a potential buyer would consider them as viable substituitons.