Was talking to one of my regular flying colleagues recently and he was of the opinion it was ok. We had a frank discussion about it and he agreed that if I wasn't happy, we as a crew wouldn't be doing it.
Doing 200 kts or even 180 is still too fast in bandit country. The visibility in most biz jets is not great and you can't exactly throw it around like a PA28! The mark 1 eyeball is very fallible as we all know. How many of you who instructed remember those biennial checkouts with PPLs who hardly ever did a proper lookout? Frightening!
I would personally prefer not to mix my jet with these characters! TCAS is only good for transponding aircraft and as we all know there are loads of aircraft legally flying without (or switched off) in class G airspace. RIS is subject to controller workload and radar clutter etc etc which is very common around the London TMA. It is far from fallible.
On balance, the least I would accept is an IFR transit ideally with an RAS!