chatname I was in a similar position to you when my dds were babies (main breadwinner in what you call a 'vocational-type job'). Dh was a student when dd1 was born and was offered the job that he is doing now just before dd2 was born. Dh was nearly 40 by this point (having been a mature student - long story) and really wanted to accept the job, even though it meant him working 'for nothing' (i.e. only to pay the nursery fees - we had two dds under 2 at the time!) in the first instance. Me not working was never an option, both by choice and for financial reasons. So my dds were in nursery full time (yes, 5 days a week - most days from 10 till somewhere between 4 and 5) from when I went back to work after dd2 was born (she was 7 months). I know this is only anecdotal evidence - maybe I just got lucky - but they are fine. They are both stable, loving and secure. Dd2 in particular (she's 6 now) has always been very 'emotionally intelligent', in the sense that she quickly picks up on the moods of the people around her and always notices if someone needs extra attention or a cuddle or whatever. She does this with her friends at school too.
I think that the nursery manager is being a teensy bit disingenuous about the attachment thing, insofar as this is a phase that most children go through, and starting your ds now won't necessarily mean that he won't have a clingy phase between 12 and 18 months (both my dds did, but it didn't last long, and I always lurked outside the nursery door and was reassured that they stopped crying as soon as they couldn't see me any more!).
Another thing to think about is whether a more home-like atmosphere might be better for your ds. When my dds were small I was adamant that I wanted them to go to nursery because I didn't want them to be in a home situation where there was another woman in 'my' mothering role [insecure emoticon]. Anyway, we were lucky in having a really nice nursery at the end of our road! However, we moved house when my dds were 3 yrs and 18 months old and there was no good nursery where we lived so we decided to go with a childminder instead. She has been wonderful. She has the status of a 'special auntie' - the girls love her, but they are in no doubt as to who their mother is! The advantage of a cm is that your ds would be in a home environment where the carer is more likely to follow his routine and his/your preferences, rather than him having to fit in with a nursery's routine (e.g. all the toddlers sleep after lunch - which never worked for my dd1, who dropped her afternoon sleep at 12 months ).
But I suppose what I am saying overall is, don't be freaked by the research. You have to do what works for you and your family. And, if you can (it's taken me a while to get to this stage!) be proud of the choices you've made. You are setting your ds a great example of equality within the family, of what women can achieve outside the home, and so on (and this is not to disparage people who make different choices - it's just what's right for you)... all of which will stand him in good stead and hopefully help him to become a well-balanced adult and an understanding husband and father in his turn.
OK... I've gone on far too long, but I hope this is in some way reassuring.