Interesting you should choose Winston Churchill as an example. There are a number of significant clones of Winston Churchill resulting from sibbing 'Redoubtable' and 'Indomitable'. These, termed F2, include clones like 'Atlas', 'Commonwealth', 'British Enterprise', 'Eminence', and 'Wyndmoor'. Wilson liked Winston Churchill so much that he repeatedly sibbed them, and 'British Enterprise' was awarded at the same time as its parents. There are also sibbings of these, resulting in a number of unawarded clones, but very nice, that I saw in the collection of Robert Ernst; the awarded clone 'First Minister' S/CSA, is an exceptionally fine F3, with 6.5 cm wide petals, and far nicer than either 'Redoubtable' or 'Indomitable' and other clones like 'Santa Barbara' and 'Red Jamboree' are F3 clones as well.
In addition, other instances where complex paphs have been sibbed and selfed, often repeatedly, have resulted in fine offspring. When Paeony 'Regency' and 'Rufus' were sibbed, F2 clones like 'Debonaire', 'Clover' and 'Mulberry' resulted. Ratcliffe in fact more or less stopped using 'Regency' in subsequent registrations as a parent, and switched to using F2 clones because they exhibited much improved stem length over 'Regency'. In fairness, I don't know if 'Mulberry' is F2 or F3.
Paph. Hellas 'Westonbirt' has been selfed and sibbed now into the 6th generation; F2 plants include 'La Buena Tierra Sunset' and 'Treva', F3 plants include 'Sunset' and 'Rex', F5 plants include 'Brown Eyes' and 'Jane', and F6 plants include 'Tokyo.' I'm sure I'm forgetting some, as I'm writing from memory.
Lastly, Paph. Valerie Tonkin, when sibbed ('Althea' x 'Dove', according to Val herself), resulted in an AQ grex, with 14 clones exhibited at once, demonstrating a significant improvement in complex paphs. Many of the subsequently awarded Valerie Tonkin clones result from F2 and F3 crossings; I have made both F3 and F4 Valerie Tonkins, which are seedlings still.
Other grexes with significant inbreeding (usually in F2 or F3) include Pacific Shamrock, Stone Lovely, Gege Hughes, and Emerald Lake.
So, in my opinion, making selfings and sibbings of complex paph grexes is a very important goal in making fine paphs. Unfortunately, as with all complex paph crosses, a significant number of very low quality offspring result. Gauging the results of a complex cross, sibbing, or selfing, from just a few offspring is not effective, as every complex cross will result in some very ugly flowers. That's what the compost pile is for!
