Ask HN: Should I trust my competition?

I recently landed a rather large client with an incumbent host/design/support company. This is your typical large hosting operation that offers minimal Drupal installations with crappy/ugly design, overpriced dedicated hosting, and rude customer service.

I use Rackspace for my clients and when I called their incumbent hosting provider to get answers on their DNS they went crazy on me. My client decided that they wanted to stay with this other hosting solution to keep from disrupting e-mail, and that they had a long standing relationship with them. This doesn't bother me.

My application requires a database, but their current Drupal installation is already using their 2 allotted databases (despite the fact that they are overcharged for their entire situation).

After having some back and forth with both my client and the host, the host said,

"Well, I'll call [your client] and tell them that they need another database and how much it will cost them... he'll roll his eyes, wine, and then say ok."

On top of this they want to version control my solution using SVN on THEIR servers. My entire experience with this larger web host has rubbed me the wrong way.

They know that my solution is completely custom, stream lined, more focused, and probably requires less server load/CPU cycles than what they offer their customers (think 'less is less').

Frankly, I feel nervous literally handing over all of my code/brand to them as they've proved even just in that one phone call that they don't have the client's best interest in mind.

My question to Hacker News is - how can I trust them not to copy my code and use it for their future clients (its very lightweight and highly customizable)? Should I hand over my custom made solution to a web host/design company just to finish the contract with my client? The client is the #1 hit for their search term and pulls over 50gb of bandwidth so I figure I could get a lot of future leads with them, but dealing with their current provider has continually left a bad taste in my mouth (probably because I'm stealing their business).

I'm sure there are plenty of experienced freelancers doing similar business here, and I would really like your guys take on it as I trust your experience, wisdom, and advice.