Well, to cover your points:
We discussed the risks (albeit minmal)
Aneasthetic risk is very very low, male rabbits are particularly quick to neuter minimising the risk even more.
the possibility he might not bond, me probably becoming attached to the buns I try to bond him with
The majority of rabbits bond without to much trouble. Males are easier than girls are they are less territorial. The easiset way to bond it to take him along to a rescue and introduce him to the girls there. Then pick the one he gets along with best. It's only a big issue if your fussy about what second rabbit you want instead of letting him choose.
the cost of more than one bun
That is an important consideration, potentially you can have twice as many vet bills. Insurance companies will sometimes offer discounts for second pets though.
what to do with the buns if he didnt bond with them
See above. Most rescues will let you bring him along and if not will let you adopt on a trial basis.
why i "thought" he was bored, the amount of time I am able to spend with him
If you're able to spend lots of time with him great
Are you willing to do it in the middle of the night when rabbits are most active? Can you communicate in rabbit? Are you willing to binky around the garden, take it in turns to keep watch, lick his ears and sleep with him at bedtime? Rabbits can't play make-believe, personally I think the best toy for a rabbit is another rabbit.
There isn't that much scientific data on pet rabbits but there are studies done on housing lab rabbits that show when kept in pairs or groups rather than singly they moved about their cages more, spent more time investigating things, and showed less abnormal behavours (usually the result of boredom). Another study provided several areas for rabbits allowing them to hang out on their own if they wanted and found they prefered to sit it groups of 2-3.
I'm not totally anti-single bunny, it doesn't work in every situation but I think the prefered way of housing them is with the company of other bunnies.
Elve... I know you have a couple of singles but they'll be aware other bunnies are around and get to investigate the smell when they're out exercising plus you're home all day. I think Benny & Mia get to chat to each other through the mesh too don't they?