With web services products coming out every day to run aspects of your business - this begs the question:

Do you choose line of business (LoB) solutions (best-of-breed) or bite the bullet and try to find a all-in-one solution that can run at least 80% of your entire business?

This is a very difficult question to answer because it wholly depends on the circumstances (and requirements) of your organization, budget and desired business goals.

 Advantages of LoB multi-tenant solutions

• Generally newer and therefore more consumer orientated (easier to use) with great social media capabilities.
• Cost effective. Time to value is very fast. Subscription and deployment both.
• Can resolve important issues very quickly. Such as Customer Service issues, CRM, Marketing, eCommerce and HR
• Tend not to cause too much disruption. Or if they do, its confined to one department.
• If they fail, the impact is not huge and generally confined to a department.
• Not as sticky for a customer. Easier to change technology if you are not happy with the software or service levels.

Disadvantages of LoB multi-tenant solutions

• Integration may be required and can add significant cost.  note: integration is getting easier though.
• Best to stick with LoB solutions that are silo'd. Therefore the need to integrate is minimal.

Advantages of "Suite" multi-tenant ERP solutions

• Crun at least 80% of your business on one platform.
• Significantly less integration requirements.
• Great for businesses that "naturally fit" a All-in-One. Both culturally and functionally.  Maybe not good for larger (and established) companies.

Disadvantages of "Suite" multi-tenant ERP solutions

• More transactional based, more complex and therefore less user friendly.
• Change management issues. You are effecting everyone in your organization.
• Generally are more jack of all trades - master of none. Which may pose issues with certain requirements.
• More expensive to deploy (but less expensive if complex integration is required)
• Less available options on the market.
• Generally not socially aware without custom development.
• High degree of vendor lock-in.

"Naturally fitting LoB solutions"

LoB solutions do have natural sweet spots. In other words, will require little or no integration but yet offers maximum horse power, easy to use, easy to deploy and offers the scalability you may need.

examples of such areas are: CRM (in some cases), HR, Marketing, Customer Service Automation, Web Site/Store (CMS).

In all these cases, they can (generally) be successfully purchased separate from the ERP.

Combination/hybrid solutions

Most modern "Suite" solutions do not have to be enabled to run in "Suite" mode. In other words, you can purchase a "LoB" solution because its segregated but also run say Order Management and Accounting in the "Suite" and not CRM or Marketing. This has the effect of reducing the potential integration points and can create quick time to ROI.

Final thoughts

These decisions need to be carefully balanced and professional help should be engaged to answer and advise on key questions such as:

What are my business objectives? Better customer service ? More revenue? eCommerce capability? Current processes too expensive ? Need to do something for a particular department ? What about the future?

What is my budget? LoB's are fine until you integrate.  What is my time to value? 

Does my business naturally fit a "Suite" ?

The combinations and permutations of solutions are impossible to count.    You do, however, need to make the right decision otherwise you could be embarking in a journey you do not want ot be on.

To run an analogy. Would you perform open heart surgery on a family member ? Or have someone unqualified do it ?.