Yes, I did two ST's a few sessions ago now. It is probably less intensive than sitting CA1 in one session to be honest as you will have the diversity of two subjects to keep you motivated through the session. I am in pensions rather than general insurance but still one ST was related to the work I was doing and one was not so it was a similar situation. That said, the ST's are still on the theoretical side so you may not be able to rely so heavily on your day-to-day working knowledge to get you through as you would with the SA.
Yes, most definitely. ST7 and ST8 will both be required knowledge for SA3 as from 2010, so if you intend to sit SA3 (ie assuming you stay working in GI), then you'll really have no choice! The alternative would be to so ST3 before the change, but you'll end up having to study ST7 and ST8 anyway in order to do SA3. And you'd have to do another ST out of your area, like ST5. Hope this helps Ian
A few years ago I sat ST2 (re-write) and ST5 (1st attempt) in a September sitting whilst working in pensions in at the time. Passed ST2 and got a FB on ST5 if I remember correctly. It's do-able from a time perspective, but takes a lot of hard work and giving up your social social life. If work is likely to be anything other than 9-5 during that particular session I would advise against it! The STs are also more technical than CA1, so although the course for 2 ST's is less than CA1 you'll need more time to study & understand it.
Why waste your time thinking about these issues now? There are way too many unknowns. A year or two from now you'll have a better idea of how you compare to the 'average' student and what workloads you can comfortably handle given your work & personal commitments at that time. Certainly ST3+Other is out for you so you're looking at ST7+8 if you still wish to stay in GI at that stage. Currently I'd say CA1 is manageable in an April sitting but probably not a September one. But who knows how the syllabus and course will have changed by the time you come to sit it. Stay focussed, pass your CTs, deal with the rest when the time comes.