I can recommend the game as well. I only found out about the game last weekend and immediately bought it. I must say I'm not a fan of the FM sound, but that's probably because I grew up with the EU version of the game and played it many many times (not only on my Master System II but also on the Wii virtual console).
Thanks for the automap feature I even discovered a hidden passageway in a sidedoor In Medusa's tower that I never saw before (back in the day my brother and I had hand drawn maps and never discovered the fake walls or this side door). The 4x multiplier does speed up the game. It also lowers the encounter rate. If you would combine that with faster walking speed (I haven't) it means you can run through the game pretty quickly. I hardly needed to grind. The only real grind I did was to level up and buy equipment to fight the Saccubus. I always try to defeat him ever since I found out he's defeatable, even if the rewards are small.
That reminds me, the maps on PS Cave also don't show it. When going up to the 4th level of Medusa's tower, take one step forward and turn to your right. There's a locked door and behind it a small corridor with a chest.
http://www.pscave.com/ps1/dungeons/images/medusa5.gif