Jaba,
As per my other posts Oil changes and filter inspections ARE a required thing either under the Manufacturers Maintenance schedule or AD/ENG/4 as an engineer you should know that.
Fine wire plugs are good for over 100 hours but "champions" are not? Since Champion is a brand that manufactures both fine wire and massive electrode (the other type spark plugs) this make no sense at all. If you are suggesting that fine wires need less maintenance than massive electrode plugs then this is also untrue. Both require cleaning and gapping, both have electrode wear (faster in massive electrode but spread over two electrodes instead of one in the FW)
As for the magnetos, type of plug fitted has nothing to do with the rate of wear in points, gears, capacitors and other components so advising that less than normal maintenance is "no big deal" is just plain wrong.
I know what I am looking at during oil analysis, engine monitoring, and bore-scope inspections and none of these things will identify a cracked crankcase, cracked cylinder head (not yet separated), holed muffler or any one of 100 other things that can kill you and can only be found by good old MK1 eyeballs.
Not to mention the airframe parts that would also be inspected at the 100hr
It may be legal to operate a private aircraft over 100 hours without inspection but it is definitely not prudent.
Also feel free to PM for advice