Seeking Referrals for 401(k) Record Keeper/Advisors for Small Businesses?

I'm trying to get a sense of which companies are best for highly acquisitive companies that are just starting out (with less than $2M in the 401(k) plan and less than 200 employees)? The metrics I'd like to know are (1) Recordkeeping/advisory fees - are they bundled or separate? (2) What has your experience been with adding new employees following an acquisition? NOT asking about PEOs, just standalone 401(k) providers.