My current paper is Ilford FB warm-tone multigrade. Overall, it is a very fine paper, but I do find toning it difficult. With FB multigrade 'normal' tone, Selenium enriched the shadows and brought up fine highlight detail. It also gives the paper a beautiful cool purple-blue colour. Fantastic. Unfortunately, warm tone paper in selenium is less predictable. A short toning 'crisps' the image, but then the deeep shadows will start to chang to a coppery-red. This colour NEVER appears in the highlights, and can leave the print with a (for me, too) dramatic split. I tone each print carefully and snatch it from the selenium at the first hint of colour change.
Agfa Multi-Contrast Classic was great. It too would sometimes tone with a split, but it was far more subtle and, to me, attractive. Right now in the darkroom I have a box of Adox Fine Print Vario Classic neutralton. Came last week and I haven't broken the seals, but since this is the first day of a weeks vacation ( yee-hah!) I'll let you know what it looks like soon. This stuff is billed as having a very high silver content for extra rich blacks. For details, see www.retrophotographic.com in the uk.