I might swap out Ice Analyzer in my Nasir deck and try this out, but not really sold on it. Maybe if it were not a unique and could be stacked it would be more compelling.

EDIT: I did the swap and played a few games with a one of in Nasir. It came out in two of the games and was maybe better than Ice Analyzer but not necessarily.

There were two key things about the card, both fairly obvious but no less significant for that:

1) get thru one Pop-up Window

2) works ok with Personal Workshop

Having said that, my experience with Nasir has been that later in the game after the corp has rezzed most of their ice, Nasir works like a normal runner and often has a fair amount of money on hand at which point this card goes dead aside from a surprise hit.

The way I play Nasir is to get a Kati out early and on dead turns just click her to load up 3 more and do that off and on throughout the game whenever I can spare the click. Meanwhile I'm running and forcing rez's. Eventually the corp's board is stable i.e. mostly rezzed and I tap Kati for a bundle of cash that I use to just force thru accesses. I run some Sattelite Uplinks and a couple of Forced Activations and some Same Old Things. If the corp starts dropping new ice, I expose it; if it's low or 0 strength I FAO it to keep my bank, if it's high strength I run on it and spend my cash on ice that retains its strength and / or SMC or Personal Workshop.

In that style, Order of Sol is ok but not stellar whereas Ice Analyzer helps to pay for programs grabbed by SMC.

Basically, late game either are pretty dead draws, early game Ice Analyzer really helps smooth some proactive play decisions while Sol is more of a reactive safety net. I prefer a more proactive controlled style of play but surprises happen and it sucks to get caught by a surprise pop up or in some ways worse Pup when playing Nasir.

So I'm still on the fence. I'm going to keep Sol in the deck for a few more plays and see how it goes.

One thing about Sol which is worth noting is that it works once each turn, including opponent's turns.  So if you are using Personal Workshop you can basically trigger it once on your turn and then once on your opponent's turn - so effectively +2 credits for each of your turns.

Order of Sol is an underrated card, and is great with Nasir. 

Want to play a Sure Gamble and have 5 credits? You pay those 5 credits, therefore ending up on 0, get your 1 credit for Order of Sol and then get 9 for the Sure Gamble. 

If all ice is rezzed, it can still be useful - go to 0 while breaking subs, gain a credit for free.

Obvious elements - can now get through that Pop-up window. When you encounter an ice, you get +1 credit (people were splashing for Xanadu for this very effect). And, of course, there is the synergy with Personal Workshop on your own / Corp turn. One thing to note is that if you do hit a Pop-up window and want to have that credit to get through, you need to leave 1 credit in your bank, then encounter to drop to 0 and get the OoS credit.

I read your Order of Sol comment, you left us all hanging...

Anyway so my comments/ideas were:

Have you had any success using Order of Sol aggressively, because whenever I play it I always get into the mood of one more turn of setting up/activating Order of Sol will be alright and then I realise I've left everything too late and end up losing? This was why I thought about it with Study Guide as a way to stay more aggressive (running) rather than always using it for installs, because both Study Guide and Personal Workshop are good with Nasir (or is Gordian Blade still the better choice). So with your aggressive play-style can you still get enough activations for Order of Sol to be considered worth playing, without spending too many turns not running (or possibly no turns) and am I missing any key cards to help with this? This is also because you say you sometimes hold most of your creds, which effectively means Order of Sol is doing nothing.

What do you install off of SMC with all your creds, Femme or something like that??? And if you have SMC lying around doesn't it severely inhibit your mem?

Have you considered Snitch as an alternative to exposing (possibly with Au Revoir) as a way to keep low creds and not get screwed if you run the wrong ice? (my only issues with this are that it can slow and mem heavy, but for some reason I really like Snitch/Au Revoir)?
I did like the idea of FAO, and tried it with Social Engineering, but I guess this was probably a poor idea, as you indicate FAO'ing low cost ice whereas Social Engineering is for high cost. I found both together were taking up a lot of space, maybe playing less and on separate targets is the way to go, although Social Engineering never really played as well as I thought it would.