In my opinion the probes used have more effect upon EMI and other noise than the scope. As others have said the scope was designed in conjunction with Agilent and very well designed and manufactured. However, the cheap price will mean cheap probes, so they will introduce noise and other issues. Of course a 'good' set of probes can exceed the cost of the scope when new. I picked up some HP probes on ebay for a good price (though still more than a new pair of cheap probes).
And before you consider the hack to increase bandwidth, beware that some folks have reported that their attempts to perform the hack caused the scope to brick. No idea if that is a change in firmware (copy protection) or simply a mistake in implementation, but the risk should be considered before the attempt.
BTW, the hack worked fine for me, but I have a version of the scope from before the hack was published...