Upgrade from 1.1 to 1.4 final? Can I try or too risk?

[molino24]

Hi,

My webshop running in 1.1 version since 2009. I made a lot of not professional modifications in the first time. I rewrite a lot of tpl, php, module, translations files...etc. The shop damaged a lot of times but now still running. I tested the 1.2, 1,3 and now the 1.4 also. I would like to start with a new 1.4 clear shop. And after this, I don't do any lame mods.

What are your suggestion? Update or install a new?

If update: I worry about the modifications. I don't remember where I made mods since 2009...but I know it was a lot of...

If install a new: The shop has good first positions in the Google, I will lost positions and new costumers for months.
And I lost the costumers, all orders and stats because I can't transfer on the new installed shop.

I waiting suggestions from professional users. And can I order an upgrade job direct from Prestashop? Is this possible? My shop is very popular and we sell in big quantity, so it's very important! When we started, the business was not big but I must change now... I hope that I will get serious answers.

Thanks in advance.

Best regards,
Zsombor