The main difference between RCOS (also OGS https://opticalguidancesystems.com/ still in business, and mostly making 20+ inch pro scopes and mounts, so they don't do adds in amateur publications anymore) versus the 'less expensive' Chinese RCs are the mechanical parts, including the tube.
I was told (by each party separately) that OGS and Explore Scientific were considering a joint venture, with ES providing the Chinese optics and OGS the tube assembly - the end product sold by both. In the end it never happened - but both told me that the Chinese RC optics are very good.
OGS no longer states the source of their optics -- probably because they come from their competitors. However, they do state on their website "Each system is diffraction limited, having a final wave error of 1/4 PV and 1/30 RMS. A Zygo interferogram with fringe analysis is provided to certify the optical quality of your telescope."
Also, while OGS recommends the RC, and advertises Classical Cassegrains too, they state "Recognizing that no single optical design is best for all applications, OGS can supply Newtonian, Classical Cassegrain, Wright-Schmidt, Maksutov or Ritchey-Chretien systems configured to specifically meet your needs."
The big cost elements in OGS (and RCOS) is the mechanical structure - made in the finest USA machine shops on the best equipment available - and are very strong to eliminate shifting as the scope moves (or is transported). The machining is aerospace industry precise, and the tubes don't bend. ?The OGS tube is a combination of Al, Mg, and carbon fiber designed to be compatible with their pro customer's IR concerns.
Read the stuff about collimation on this page: https://opticalguida...ystems.com/faq/
The owner of OGS is well-liked in his local astronomy club because he takes fellow members' SCTs into his shop and collimates them on his double-pass rig. "I can often improve their performance by offsetting the secondary a tiny bit to compensate for the mis-collimation of the primary."
One final note about price -- OGS (and I think RCOS) prices for telescopes 16-inch and larger includes on-site installation, with a guarantee that the scope will work before they leave. They will show you how to run everything -- and if there's time, they do a T-point run (OGS mounts use the same electronics and motors as Bisque).
To me - it all comes down to money. For most amateur astronomers the Chinese RCs will work just fine, but may need some "fiddling" to get full performance. For 'high healed" am's, and institutions with limited funds - there's Plane Wave -- and for those with "unlimited resources" there's OGS, Deep Sky Instruments, etc.
I should mention -- the owner of OGS's personal telescope is a Tak APO refractor on a modified Tak mount. --but I've seen him at Stellafane with an OGS 12.5" RC - used just before shipping to a customer (with permission of course).
Edited by George N, 22 February 2020 - 10:25 AM.