1.5 L Wet Grinder - Santha VS Premier Wonder

[ABCD]

I am contemplating on buying either a Santha 1.5 L or Premier 1.5L Wonder wet grinder. Both are vertical models.

Santha 1.5 L grinder runs at 990 RPM and costs about $250.
Premier Wonder 1.5 L grinder runs at 1440 RPM and costs about $155.

1) Any comments on performance, quality and durability of these two models?
2) Would appreciate input about Pros and Cons of buying one of these models compared to buying Ultra and other well known wet grinders.
3) Are there any advantages in buying a horizontal wet grinder instead of a vertical wet grinder?
4) Is it desirable to buy a wet grinder model with a higher RPM?
5) From the price and RPM, Premier Wonder wet grinder seems like a better buy compared to Santha. Any comments?

Thanks in advance for your comments.