Probably not on an SRX110. You can review the performance spec sheet at the end of this document that compares the limits on each branch model.
http://www.juniper.net/assets/us/en/local/pdf/datasheets/1000281-en.pdf
Your your application, the first limit is number of virtual routers which is only 3 for the SRX110. With 4 ISPs you really want 4 virtual routers meaning a SRX210 is the minimum for this.
With the number of users you have you will llikely also need more bandwidth, but these you will have to estimate based on your user population. The key parameters I usually find limiting platform are the IMIX bandwitdth, VPN bandwidth and PPS limits. Have a look at the limits in the last few pages of table and choose the model that will cover your situation.