Haven't tried it myself yet, but I believe others on here have, so looking forward to reading about some actual experiences.
In theory, it will of course play fairly similarly, but a number of things are worth taking into account. There is the simple matter that some effects can no longer take place, like the Summon spell's "an angry demon attacks you when you roll a 1 when casting this spell". A one on either die would be harsh, while a one on each is much less likely to occur. Spells will generally be easier to cast, as casting values are mostly in the middle area of 8-12. Even more so later in the campaign, if brought down to a 5. Additionally, resistable spells empowered to a high number will be more difficult to get rid of: e.g. getting it from a roll of 13 to a result of 16 costs three health in either case, but the resistability of a spell on a 16 is 25% for a D20 but 15% on 2D10. Finally, it will make the more expensive soldiers better, as the high results necessary for weaker ones to overcome them are less likely to occur. A thug needs a roll of 12+ to hurt a knight, 19+ to reduce one to wounded in one strike and 20 to kill him at once (crit). On the other hand, a knight hurts the thug on a 7+, wounded at 12+ and dead at 16+. The likelihood of those numbers shifts quite strongly when using different dice - which isn't necessarily a bad thing, but something to take into account.