Last winter I made some prints on Agfa Fibre and RC papers and did some selective toning in Sepia , Gold and some Copper. They were beautiful and I recently reprinted a couple on Ilford Multigrade IV with the intention of tweaking the colours a little.
To my surprise I found that toner response with these papers is close to nil and ghastly in Kodak Sepia. Most of the warmtone papers tone beautifully but very differently.
I have come to realize that Agfa Classic may be one of the most under appreciated papers of current times, excellent neutral tone, good gloss and the best 'toning experiment' colours I've seen. It can be converted to ivory base with a light blue tone and redevelop.
Also the RC Premium Glossy is the only one I've used which does not have that veiled look.