Why on earth would you want to ruin a perfectly good privacy and fungibility supporting wallet and keypair chain with the inclusion of one or more privacy killing vanity addresses?
These two things do not mix. Best to completely get rid of the vanity addresses and use your HD wallet properly.
I would follow BurtW advice to the very detail and immediately quit the vanity addresses ,
a lot of late hacks to different persons came just after they visited the website which generate vanity addresses, apparently they are not safe, you should focus on Multibit HD and do all of your transactions there, is much safer than any address generated online, vanity or not.
Your statement is correct. However, you can easily and safely generate your own vanity address using vanitygen on your local (preferably offline) pc, or use the split-key method.
Thus far, i haven't seen one of those vanity addresses getting compromised.
I like my vanity address, and i use it for a lot of purposes, but mostly to stake it here on the forum, so i can use my vanity address to sign messages and prove my identity.