I have experimented plenty with a Keto diet and it is impossible to predict what level of protein will kick you out of keto. You need to test, adjust and test. The only reliable test is using a blood ketone meter. Keto sticks don't work properly. When you start out they the keto sticks show you are in ketosis when you are close to ketosis because you are peeing out excess ketones as you adapt. Once you are adapted, like everything else, your body finds a happy medium of ketone level (beta-hydroxy-butyrate) and you stop peeing the extra out - you will be in ketosis but the keto sticks won't show it. The Freestyle Glucose monitor can take keto blood strips too and is available at Dischem (test strips are insanely expensive like R180 for 10).
For me, I followed the 'conventional wisdom' version of Keto for a couple of months before buying a monitor, after using the monitor low and behold I wasn't in ketosis. Protein level was too high (I am 80kg, lean body mass of 70k) and was eating 140g per day. I had to cut it to 100g per day to truly get into ketosis. Once you are in ketosis and used to it (supplementing with salt) you feel fantastic. You no longer need to test to know. Why the salt? Because you excrete salt in ketosis (this also stabilizes over time) resulting in low blood pressure, which makes you feel crap - taking in extra salt eliminates that feeling.
ketosis is awesome for fat loss and endurance sports where you don't go anaerobic. Performance in high intensity sports, for me anyway suffered. I now balance it. It eat a ketogenic diet 6 days per week and accept my training will be impacted on those days and then carb load for for a day, and train really hard for that day and the day after - those days the training is awesome as you get the benefit of having a higher ability to utilize fat while having muscles full of glycogen. I also thing you retain metabolic flexibility this way. This approach won't work unless you are properly keto adapted as the carb day kicks you out of ketosis and unless properly adapted you just won't get back into ketosis in the next 6 days. It take me now 2 days for my blood ketone level to go over 0.5, which what is considered the cross over point. It will then creep up to 1-1.2 before the next carb load.
On a side note, never test your keto level directly after high intensity exercise as your blood ketone level is typically very low for a couple of hours after. The reason is that high intensity exercise causes your liver to dump glucose into your blood as the high intensity 'empties' your muscle glycogen. This relatively high level of glucose blunts, temporarily, your ketone levels. Conversely, if you do an endurance event, say 3-4 hour bike ride while in ketosis, only consuming water during and test ketone levels afterwords, you will show hyperglycemic levels of blood glucose (levels on their own that would put you unconscious) and ketone levels really high (the highest I measured was 4.5.