I was just talking about this with someone the other day.  But first, who do i use?

I used Square when I was an integrator..nowadays, I use Freshbooks/WePay(Chase).  I like both and would recommend either without hesitation.  Freshbooks has been one of the best companies I've ever worked with across any platform.

Yes, you pay approximately 3% in fees.  I started taking them in 2009 when Square started.

From my personal experience, when I was a small shop Square was great for my business. The first year I did an additional 170k in revenue than the year before. I attribute it to taking cards.  People tend to spend more with cards.

Lastly, the best way to deal with payments IMO is to bump your quotes 4%. That'll cover all the costs. Then it also gives you wiggle room if you want to offer a discount if you think it can get you the sale (if the person pays cash,check).

You want 10k.
Invoice is 10,400.  (including the 4% for the card fees).
Mr. Cheapo balks....Can you do better?
I can knock off 5%.
Now you've given him a 5% ($9880. discount and you've only lost $120. But he's saved $520.(But he's gotta pay with check).

Otherwise, it's 10,400.  You get the 10k.

In this day and age, make it easy for people to do business with you.  With Square, you can also integrate it with your website, so you can accept payments that way too.

IMO, you're in the technology industry.  Embrace the technology.