Stripe was always going to release this. Balanced however, has more advanced tools to deal with marketplaces (i.e: you need to write less code to power a marketplace on Balanced than Stripe).
This is not a big deal though, the battle will end up being who can scale globally faster.
> ..the battle will end up being who can scale globally faster.
I think there's more to it than this. The cost of switching from one payments provider to another is decreasing all the time. Competition appears to have driven costs (i.e. the fee/commission per payment) down to roughly the same level for everyone. There's some room for differentiation on the product (not so much ease of set-up - which is a one-off thing - as the admin UI and featureset), quality of customer service (I know someone here in the UK who switched from Paypoint to SagePay for precisely this reason) and the accuracy of fraud detection (i.e. minimising both chargebacks due to the use of stolen cards and erroneous rejections of legit payers).
However, I think that there's a strategic competitive advantage to be gained through operational efficiency (i.e. reducing the cost per transaction to as close to zero as possible) and generating revenue from sources other than the fee/commission (for an example of this, see my blog post on how Paypal makes money on cross-currency payments: http://jackgavigan.com/2013/03/12/how-paypal-makes-money-on-... ).
This is not a big deal though, the battle will end up being who can scale globally faster.