Like Dan I do that all of the time and in fact many times I will duplicate an instrument track and use two or more different programs for one sound. That way I don't have the identical sounding instruments as say a violin from one company may/will sound a little different than a violin from a different company. All violins in an orchestra do not actually sound identical, a chorus effect, because every violinist does not place their finger in exactly the same place on the neck. They are extremely close but not necessarily identical. Plus the string maybe go ever so slightly out of tune during the performance.

I doubt that you will find anything about the use of different company's software in conjunction with another company's software.

Also when you use only one instrument from a collection of instruments you are not loading the entire program, just that one instrument. Thus the impact on your system is much less.

I still say buy the fastest CPU with the most ram and the largest HD(s) you can afford. I did that in 2011 and I am still using it today.

I want my last spoken words to be "I hid a million dollars under the........................"

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware