I dropped my bike last month and damaged my pride significantly mainly because it was stationary and it was in front of a whole heap of onlookers.
Apart from my pride I completely demolished the left hand mirror as it hit the gutter.
I managed to repair the outer housing and flicker light (temporarily) and then ordered replacement parts. As I was in a rush they cost double what I would have paid from OS dealer however they were here in 10 days. Cost $450- ouch. Being a daily rider I needed a new mirror at least until the new one arrived. Luckily this happened on a Friday.
I approached the local auto glassier and he said he could replace the mirror and I wouldn't be able to tell the difference - except it wouldn't be tinted like the factory one. He stated they did it all the time for car external mirrors. He did it for $40 - Not bad. Had a look and it seemed OK - fitted it to the bike for my daily commute on Monday.
Come Monday headed off and too my surprise the left hand mirror was useless. The focal distance for the replacement mirror was way too close, making it impossible to gauge the distance of objects behind me. Heading through the Brisbane tunnel, the lights from the cars behind me was completely overwhelming.
I have attached an image of the difference.
The right mirror is the Honda genuine part and the left the car mirror. My bike in the picture is approximately 30 feet away from the mirrors. You can't see it in the daylight however, the right mirror shows significantly less glare at night.
My point:- Whilst you may save a bit of money - If safety is of concern - always fit the genuine Honda part. Whilst is is on the ST1100 I'm sure the same applies to the ST1300.
Cheers,
A.