I think having a stallion for everyday riding isn't at all bad- any stallion worthy of his... jewels.. should be able to be ridden/worked everyday around other horses with absolutely no problems whatsoever.
This is assuming the rider is competent as well, as you do have to pay alot more attention (mostly because of other people) when you have a stud.
The only thing I would say (assuming your horse is very well minded and very well mannered, which I assume since you are even considering in the slightest bit allowing him to keep his jewels) is that some places just don't allow studs because of the risk. Around here, if want to go for a ride in a nice area- most of the best areas for a nice ride are off limits to studs.
I don't think at this point in his life (with his age) his demeanor would change any, but if I wasn't planning on breeding him- I would geld him if I were you. Then you also don't have the risk of accidental breedings where you may possibly be liable for vet cost is he got out one day and bred a mare whose owner didn't really want to be bred. You could also take him where ever you wanted without having to worry about if studs were allowed or not- and you might even be able to RELAX a bit when you are out in the open with other horses.
The cost of gelding vs. the risk of owning a stallion you are not surely intent on breeding, to me, is a no brainer decision. "A good stallion makes a great gelding" as they say.
I've met really awesome studs, and really terrible studs (personality wise). Just like I've met really awesome mares/geldings and really... err... there's-a-possibility-of-death-just-by-looking-at-them.. types, too. But, I wouldn't keep a stallion a stallion just for the sake of a stallion... way too high maintenance for me!