Hi,
I have had a number of cars running on LPG since 2006.
I had a 2003 Nissan Cefiro V6 running on LPG the engine ran 250,000 kms before I sold it to a friend.
They recently upgraded the LPG system to a local made system. The car has now covered 325,000 kms.
No problems with the valves yet.
Most Bangkok taxi run on LPG and a lot of the taxi have done over 500,000 kms.
2 years ago I got a Toyota Camry 2013 model it was costing nearly 4 baht a kms
I had the car converted to LPG for 20K baht and it cost 1.5 baht a kms.
The car is running fine with no problems.
I also had a Ford focus 2.0 for a which was already on LPG when I got it. The Ford was a big bag of trouble on LPG and petrol.
I think if you find a good installation garage for the LPG you should have no problem.