Of course, it is your decision ...
I have used CNG vehicles both personal and official ... it has been my observation that in Pakistan specific scenario, where the availability of CNG is questionable, the cars develop an "attitude" about the type of fuel. Cars run only on CNG develop various problems i.e. deposits in the combustion chamber, and drying up of rubber parts in fuel pumps, etc. Their ignition timing has to be set for EITHER petrol or CNG.
The best thing about my experience with CNG in Laadli is that the ignition timing is not an issue. The ignition timing is change when you switch between fuels.
As you must have observed, I keep the fuel tank FULL at all times. For filling an empty tank, I get ten litres of Hi Octane, and the rest is filled with Premium Petrol. This mixture works very well.
Even when there is no "CNG Loadshedding", I run my car on petrol one day in every week. This helps against deposition of carbon residue in the combustion chambers, and protects against any damage to the engine.
It must be understood that CNG powered engines have shorter life than those run on gasoline. So, in order to achieve good results in terms of fuel cost economy and the life of the engine, it is best to use CNG for six days a week, followed by one day on gasoline.
I belong to Lahore and Gujranwala. Whenever I go to the hometown, I drive to Lahore on CNG, and drive back on gasoline. The reason is that the CNG in Lahore and Islamabad is different. Islamabad's CNG has very high BTU (British Thermal Unit) value, than the CNG available in Lahore and surrounding areas.
The change in type of CNG with respect to different cities becomes and issue. The CNG settings have to be changed with different CNG type. In order to avoid this, I consume the CNG from Islamabad on travel to Lahore, run my car on gasoline in Lahore and on the way back. This surely saves the visit to a CNG mechanic in Lahore for changing the settings, and also gives an opportunity to run the car on gasoline for extended period of time, which is good for the car's engine life.
So ... the mashwara, please go ahead with CNG installation. Since you are in Lahore, as per my elder brother's suggestion, please go to Toyota Kot Lakhpat for CNG installation. According to my brother, their CNG mechanic is simply marvelous.