I work on both the GS and the push bike fairly regularly and worked happily for years with an old 120 piece Kamasa set until I eventually replaced it with a similar sized Halfords Professional set when it dropped to £99 some time ago. I have also, over the years when I had easy access to a Snap-on van, bought odd bits and bobs that the toolkit didn't give me. I still have an old 10mm spanner which was bought for adjusting the valves on a Honda 250T (needed a very slight angle on the ring end which only Snap-on delivered) and which still does the business on the GS. I also have a few Park Tools specialist bits and bobs for the push bike.
I'm with Steptoe on the "good set" and "bad set" of tools - it is nice to have a set of sockets you are fairly confident won't split if you have to put the torque setting up high. At the same time having a box of assorted sockets that can be hammered on to a recalcitrant nut that's been rounded off by some ham fisted idiot is a godsend.
Would I like a full Snap-on set? Oh yes, but I couldn't justify it without winning the lottery and just buying it as a luxury toy. I'd also buy the full £3,000 Park Tools workshop kit. And a big double garage to keep it all in. And a good security system...