I don't use Fiprospot, but I use Effipro (made by Virbac), which has the same ingredients as frontline, only it's cheaper. (a box of 24 vials is £98 instead of £120 for 24 Frontline for e.g) This was on the advice of my cat vet.
Apparently, the patent on Frontline has now expired, which has meant that cheaper "copy cat" flea medications made with Fipronil (the effective ingredient in Frontline) can now come on to the market and be sold. If it has the same quantity of Fipronil in it as Frontline, I'd say the effacacy of the medication is likely to be the same as Frontline.
I'd think any form of fipronil would be much the same as another. We don't sell plain Frontline any more, just the Combo, because the effectiveness of the Combo version (fipronil plus S- methoprene) seems to be much greater in our local area. If you find plain fipronil works ok for you, Fiprospot should be fine. You don't need a prescription for fipronil on its own, just for the combo version.
I agree with Alice one fipronil is much the same as another we only really use Frontline combo for cats in our practice for cats who get ticks apart from that we use Advocate and Advantix. I think with any fipronil product you must remember that the original licence was to kill fleas within 24 to 48 hours.