couldnt find either of the 2 you mention here in the uk,would the one i posted not be any good?
Of interest regarding Keilwerth mouthpieces: http://forum.saxontheweb.net/showthread.php?78501-Keilwerth-Jazz-Mpc . So they are made by ESM http://www.esm-mouthpiece.de/index.php?id=5&lang=english which is one of the mouthpieces played by Trimmy on the forum.
So may not be that bad.
The B5 is 0.080" - which is a very large tip opening for a beginner. See the chart below: http://www.jodyjazz.com/facings.altosax.html where 0.080" is included in the orange section - meaning "recommended for professionals and advanced students". It generally does need a softer reed but also will challenge your embouchure which is what helps to bend the reed to fit the steeper mouthpiece facing curve and limit any air leakage.
I have been playing the alto sax for 7 years and most of my mouthpieces are between 0.076" and 0.080", which is comfortable with 2 1/2 strength reeds. Beginners are better with mouthpieces below 0.070" IMHO - hence all the recommendations made above.
To reduce squeaks make sure you fully immerse the reed in water (with some alcohol) for a few minutes, and also make sure that your embouchure does not leak air. A moist reed is easier to bend.
I agree that the Rico should sound better than the standard mouthpiece, but just has too large a tip for you to play well. In a year or so's time it should be different.