Scrum for Specialist Teams – Effective Implementation

They're not actually user stories. They're stakeholder stories. Unless the software is actually paid for direct by users, it's rare that a story is created entirely for their benefit.

I give you a couple of examples:

• keyworded articles, which allow advertisers to have more effective adverts
• CAPTCHAs, which are there to stop moderators having to deal with spam manually.

Most technical stories actually provide a business benefit, but it's rarely for the users. Phrasing them in a different way can help. I normally use Chris Matts' Feature Injection template:

In order to <achieve my goal>
As <the stakeholder who wants the goal>
I want (<some users to do>) <some stuff>.

This explicitly recognises all kinds of stakeholders, including the development team. Now you can phrase your technical stories too, calling out the business benefit:

In order to minimize the risk of deploying something broken
As the team deploying the code
We want to spend a few days on an automated deployment system.

I've written a couple of blog posts on this: They're not User Stories, and Feature Injection and handling technical stories. Hope they help.

From your description it is not clear whether the teams are actually working on separate projects - I assume they are.

In the ideal case, I think this should be mainly decided by the teams themselves, but they would come to more or less the same conclusion (i.e. using Agile). Especially if prominent members of the teams used to work together in the single Agile team before, they tend to naturally bring with them the practices they tried and proven to work.

However, each new team is bound to encounter its own, more or less different situation and challenges, so over time they will develop their own process a little bit differently from the others. And that is fine, within certain limits. In order to make management's life easier, it is advisable to agree upon and stick to some common way of reporting towards management. But since Agile is not reporting-heavy, I don't think this imposes huge restrictions on any team.

Now, if one team comes up with a process improvement, it is indeed useful for other teams to learn about it - as long as it actually solves some problem of theirs too. So IMO the best approach would be to keep up communication between teams regarding retrospectives and process improvement solutions, by way of some designated team members (one from each team would be enough - e.g. the Scrum Masters) to regularly meet after each sprint and discuss the problems they encountered, the solutions they tried, and the results.

So if Team A tells about a problem, it is possible that Team B has already got a working solution for it, which can be applied right away. Or if Team A has an idea to solve same problem, it is possible that Team C has already experimented with a similar idea and they have gained useful experience which they can share with Team A. Etc. The point is that any team is most interested in solutions to their concrete problems, so it is best to approach knowledge sharing from this perspective: adapting solutions to concrete problems, rather than trying to adapt processes to imaginary "solutions". Development teams would be pretty normal to resist the latter approach, but not the former.