A block signer can be appointed and paid by a delegate and can be fired/reassigned at any time by a delegate.
Thats just unnecessary distraction for the delegate, who may not be the best in choosing the correct block signer. If the delegate has a skill set which would be useful, let him just do that, no need to make him seek out an able block signer and outsource.
Another advantage for separation would be that there won't be a limit of the pay or the number of employees, giving better flexibility. It also will allow for short bounty style payments, which would case quite a upheaval in the current model as a delegate comes and leaves for a short period.
What part of we cannot have shares vote for more than 101 *THINGS* because it does not scale. So saying that there won't be a limit on employees or pay is wrong. We need to limit pay to prevent unbounded dilution and we need to limit funded positions because of transaction processing time and size.
Basically if we go with what you are proposing we will end up with 101 small companies formed around delegates. So someone has to join one of these companies or start their own (which will be really hard once the others are established) to work for BitShares. A marketer or whoever should be allowed to focus only on their task and be able to do it independently because that will allow for the most people to contribute. That's also the most decentralized.
The issues you bring up about transaction time and size can easily be solved as well. Still have 101 regular delegates, where things happen every 5-10 seconds, but then have your unlimited number of employee delegates who are maybe checked by the network once a day for voting and performance and such. They don't have to be in every block because they're not signing transactions.
Also, do you really think this will make a problem with max dilution? No, it won't, only people that are needed will be paid and if it is too much pay they won't be elected, maybe we'll only have ~10 employees to start. The voters decide max dilution and how many people are employed and at what rate. In addition, dilution shouldn't even be present most of the time because this is a company and it should be able to earn enough profit (from transaction fees or whatever other income we can think of) to sustain itself.
Before I finish, the only issues I can see with what I'm saying is that this would be a lot of people for users to vote for and keep track of. for that reason, SOME, of the employee delegates would need to be formed in companies (like the marketing group 1,2,3). Still individual employee delegate should be able to exist and no employee delegate, alone or in a group, should have to work with a network delegate. There's just no point. Its unnecessary complication. Make this thing EFFICIENT AND LOGICAL.