I had 4 P. emersonii bloom this year. .... BUT all 4 had defects in the flowers for one reason or another. Also I started with about 12 emersonii that I picked up in 2 batches, 6 in 1988 and another 12 in 1998. I am down to 12 plants having lost 6 over the years due to one thing or another. A 66% survival rate over 20 years is not bad, but nothing to brag about either. For me, the older batch has the best form for its flowers, very flat, but these plants are really slow to grow. Most took 8 years or more to their first bloom and most only rebloom once every 4 or 5 years since.
The latter batch has bigger flowers, seems to grow a little faster and has teriible flower shape. They always look at the ground, are floppy, usually a bit twisted and otherwise just don't pose for the AOS photo look. The later batch seem to bloom every 3 or 4 years instead of 4 or 5. Not much improvement, but a little better.
I grow mine under 40 watt shop light fluorescents, in the 'cool' section of my basement. It actually gets warm in summer and into the high 50's at night in winter. Heat from the lights brings up temps just a little in daytime. I pot in a fine seedling grade bark mix, with charcol added. I top dress with oystershell. I use Lake Michigan sourced tap water, and 1/2 teaspoon per gallon of MSU Orchid Special every watering. I repot every 2 or 3 years. I do not divide multigrowth plants, only when a division falls off on its own do I pot it up separate. Only 1 clone has been prolific enough to produce more than one division in over 20 years.
I have had very little disease trouble.I would say emersonii is a slow growing Paph, but not much trouble, just very slow. If you get seed raised plants, from a good breeder like Sam Tsui you should find some seedlings will be more vigorous and not as slow as the ones I bought, the ones I bought so many years ago were probably divisions of originally collected plants. Not many were being produced from seed 20 years ago. So for what it is worth, that's my 2 cents.
Leo