I am in no way scared of doing anything at all on my bikes - a dealer will never see any of them.
But in my humble opinion:
Keeping receipts is fine it shows that the parts purchased are of a standard which may (or may not) be acceptable as replacements for the original. I doubt many dealers are able to use Suzuki parts 100% of the time.
However, receipts cannot show that the fitting of parts was done by a qualified mechanic and as such may not have been fitted / adjusted correctly and may subsequently cause damage to other components.
I used to service motorbikes and can remember countless times when bikes only a few years old have needed quite substantial top end engine rebuilds due to incorrectly adjusted valves. I agree that topping up fluids should be done on a regular basis but, here in the UK at least, that is as far as it goes. If something goes wrong with your engine etc. and the dealer is able to see that this was caused by someone messing around with something that they have not been trained to mess with I think any clain under warranty for parts to effect a repair would quickly be kicked into touch.
I am pleased that you are happy to service your bike yourself and that you appear to know how to go about it but it is not something that anyone should consider unless they are very proficient in what is required.
Servicing a bike or even complete engine rebuilds are not rocket science, and I commend anyone who is happy to do this as the financial savings are very high - providing you know what you are doing.
Good luck with whatever you decide to do with your bike.