i asked myself this after my second week on the diet when i was feeling a bit groggy. i decided to use a ketostix to measure where is was at, and found i had ketones in my system. then followed a frantic search for answers all over the net: to which i concluded that i'd eaten too much fat and not enough carbs in proportion to the amount of exercise i was having. and that although there were ketones, this was a sign of non-PWD's ketosis rather than a PWD's ketoacidosis (i had had perfect sugar levels that day, all under 7mmol's, so i was very confused). anyhow, with a little adjusting, i have not had one more positive ketone test, and i now check each evening - and will do until i am settled on this new lifestyle.
so, i would never recommend a ketogenic diet, because i don't think it's a positive thing to do to your body, and can give you permanent damage to your kidney/liver/gallbladder. something worth keeping in mind, especially when a PWD's body is more at risk of these things anyway.
i eat about 50-100gr carbs a day, and those are mostly at breakfast time and as snacks before and after exercise. i hardly eat any carbs at dinner, it's usually a big salad, and i eat a small amount at lunch with by large protein portion for the day. i found this post at marks daily apple very helpful in understanding how many carbs i ought to be eating. but i also think that it's different every day, and that you also need to listen to your own body's demands, and account for the amount of exercise your getting with your carb intake.