Buyer acquires company with existing plan; merge or keep separate?

[Bird]

A medium sized company (500 participants) acquires a smaller company (70 participants).

The plans are similar, and we were planning on merging them. There are a few differences that need to be kept different:

• different matching formulas for the two companies
• different profit sharing formulas (actually one company won't have PS)
• different vesting schedules (more generous in the smaller plan)

We can do all this in the document, but it's starting to get ugly and are considering maintaining two plans.

(I think) that 410(b) testing on the contributions will yield the same result, so the result doesn't impact the decision - I think it is easier to run that testing in one plan but it's probably not a big deal to run a combined test on two plans.

For the vesting, I'm not sure whether to keep it separate (in one plan or two - then I think we have a potential benefits rights and features issue) or just preserve the vested benefits and change everyone to the more restrictive (2/20).

Blah blah. I guess I'm just looking for feedback on what is "normal" or "typical" in these scenarios; it's not something we see all the time but I'm sure others do. I imagine it comes down to the individual situation but thought I would throw it out there.

[MoJo]

Costs of maintaining two plans (documents, forms 5500, recordkeepers) vs. costs of dealing with the ugliness of a weird plan document.... Add in possible growth of the small plan to "audit" size, and add that cost in (someday).

My "preference" is one plan where possible, but always "keep it as simple as possible" - so in this case, hard to tell....