Hi guys, thank you both for your responses.
I don't think I framed my question correctly though. The 301 redirect issues I am worried about are:
A. server speed- too many 301 redirects is going to put an unnecessary load on the server and reduce speed =BAD
B. being penalised- too many 301 redirects can be viewed as aggressive PR sculpting and your 301's can be devalued )(see here) =BAD
C. Avoiding 301 redirect chains- Matt Cutt's interview with Rand in 2010 said 301 chains are not a good thing as a general rule (no need to watch video, it's in the text below) = BAD
SO....
Ryan K, I agree with you in your decision to direct from old site direct to new site. However, 404's are not necessarily a bad thing (see google's stance)
Ryan P, I agree with your suggestion of a sitemap
** So my plan as far as I see it is this:**
1. 301 redirect all the original site (www.oldsite.com) pages to the new URL's at (www.mynewsitewithgreaturls.com)
2. Any pages on the intermediary site (www.newsitewithdodgyurls.com) that have gained backlinks 301 them to the new site aswell
3. Let pages on the intermediary site with no SEO value 404
4. Create a prioritised sitemap (as per Ryan P's suggestion)
This solves the problem on chaining 301 redirects, it reduces the load on the server, and it avoids penalisation due to too many 301's
That's how I see it going down anyway. Would love to hear if you think that's the right plan of action.
Anyone else feel free to chip in aswell!!