I haven't voted, because I'd suggest going for a Powerengine 60 2x12, and probably leave out the EHX pedal.
I have tried out almost all of these options in the past, when looking for amplification for modellers (Vox and Line6, not Digitech unfortunately).
I would definately advise that you stick clear of anything with a tweeter, like keyboard amps, or powered monitors, or anything similar. Tweeters will produce a harsh brightness, that I always found impossible to control.
Also avoid any traditional guitar amp. Putting a modeller's signal through another pre-amp, however clean it may be, just does not bring out the best from the modeller. A dedicated tube rack power amp, even the Marshall 20/20 into a cab (or cabs) is, I believe, the very best solution but possibly beyond your budget. If you went used, you would be looking at much the same money. Something like -
http://cgi.ebay.co.uk/sterio-Valve-power-amp-peavey-classic-60-60_W0QQitemZ140229072344QQihZ004QQcategoryZ68247QQssPageNameZWDVWQQrdZ1QQcmdZViewItem , plus a cab or two. This would also give you the easy option of running in stereo should you want to.
IMO, the Atomic and the PE60 are also excellent for the application you are wanting.
I have owned an Atomic 1x12, and have a friend with a PE60, so I do have some experience of both.
I would say that one is not better than the other. I relly don't think the PE60's lack of tubes makes it any worse than the Atomic. I'm a great believer of using as big a cab and as many speakers as I can. More speakers = bigger sound. Here is one area that the Atomic and the PE60 differ (apart from one being tube and the other SS). An Atomic has a speaker out, for a traditional guitar cab. Stick a good 4x12 on this baby, and you will be pleased at the results. The PE60, is basically cheaper than the Atomic, so you could afford a 2x12 to start with. But the line out from the PE60 is only that, though - a line out ..... to feed another PE60, or other powered device. So you are limited in what extension devices you could use, and most of these would have tweeters (except another PE60).
Another factor is that, overall, I believe that a PE60 would be more reliable than an Atomic. My Atomic never had any problems, but I have heard a lot of reports of faults. Tom King at Atomic is helpful at sorting these out, but it could take weeks/months.
SO my vote would be for, ideally, a tube power amp and a couple of cabs (whatever size you can cope with). Second would be a 2x12 PE60. All without the EHX Blackfinger. I have run modellers through tube pedals and pre-amps, and I don't think they really add anything to the mix. You might like one of Radley's Harmonic converger's. I never used one, but many folks do swear by them.