Can I use Bench.co + Xero for my business?

This is a great question. The world of accounting/bookkeeping can be a confusing array of options for non accountants.
Let's address the software question first. Let me start by saying that my firm is relatively agnostic to software, we work with dozens. I'm familiar with Xero and my firm has worked with it, and if someone comes to us already on it, we stay with it. It's a solid piece of software, certainly works. And it's a very fashionable choice right now due to inroads their marketing has made with the startup community. The big dog in the market is QuickBooks On-Line (QBO), and when I say big dog, various version of QuickBooks have easily 10x the number of current customers that Xero has. Why does this matter? The usability of the software from a user experience is about the same, but Xero is still trying to play catch up to QuickBooks On-Line in terms of features. For instance, they have payroll rolled out for "a few states and are adding more each month". Anything innovative that Xero comes out with QuickBooks is going to quickly copy and add to their product, because they are huge and have the resources to quickly adapt. This is not a situation of the iPhone putting Blackberry out of business, QuickBooks isn't going anywhere. Likely end game is that at some point QuickBooks acquires Xero and moves everyone over to QBO. Lastly, every bookkeeper knows QuickBooks, some know Xero, and there are hundreds of developers developing software that integrates with QuickBooks. So, while Xero is a perfectly adequate piece of software, we’re talking the platform for your accounting, go with QuickBooks On-line.
The subject of a bookkeeper is tricker. Do you go with a person or a process solution? Full disclosure here, my firm does outsourced bookkeeping for a living, so you have to take that into account when viewing my answer.
I haven’t worked with Bench.co, but it looks very intriguing, and pricing is quite aggressive. They also look very easy to engage with. The down side is that is appears to be a person based solution. You get assigned a bookkeeper, and then good luck. The skill of individual bookkeepers varies widely from damn good to truly awful. They often hook up with several services like this, so their loyalties are divided. Additionally, they are often working with up to a dozen clients, and what typically happens is one of their clients starts growing quickly. All other clients get pushed aside while they focus on their largest client because they can’t afford to lose them. A couple of other disadvantages are that, because they are on their own, you are limited to just their skill set, they have no one else to check with in sticky situations, and when they go on vacation, your accounting goes on vacation, too. These are all things that may be fine for you if you’ve got a relatively small business that doesn’t need daily attention to its accounting.
The other alternative is a firm that specialized in outsourced accounting. There are several firms out there, you can find them (and us of course) with a simple search of the internet. The advantage to the better firms in this space is that they typically will assign you a team of bookkeepers/accountants so that you have backup in case one member of the team is on vacation or leaves to take a full time job somewhere. These solutions also will typically come wrapped with software they would suggest for your business. Finally, you aren’t limited to knowledge base of the one person working on your account. You have a team, and really the knowledge base of the entire firm at your fingertips. Of course you pay a little more for this, but the hourly rates are often not that much more than individual bookkeepers. And in the long run you may end up spending a lot less by not having to come behind a bookkeeper that maybe wasn’t so good and clean up the mess. So if you plan on scaling your business beyond a few $200k a year, it may be best to start out with a firm based solution rather than an individual solution.
Side note on Bench.co: I can’t tell what software platform they are on. If they are using a proprietary platform, you will find it very hard to move your accounting to another solution if you’re not satisfied with their solution. Something to ask if you go with them.
So, I think that about covers it. I’ve probably told you way more than you wanted to know, but I’m always available to schedule a call if you want to dive in a little deeper. Just let me know.